ENGR00255484-2 usb: ehci-arc: add NULL pointer check for pdata->pdev

ENGR00255484-2 usb: ehci-arc: add NULL pointer check for pdata->pdev

The pdata->pdev is initialized at platform code, if init
fails at first, it will be not initialized, and platform exit
will not be called. This also fixes an oop when config usb
module wrongly:

Unable to handle kernel NULL pointer dereference at virtual address 0000005c
pgd = ba1c4000
[0000005c] *pgd=4a145831, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] PREEMPT SMP
Modules linked in: ehci_hcd(+) usbcore
CPU: 1    Not tainted  (3.0.35-02451-ge361da1 #60)
PC is at fsl_usb_host_uninit_ext+0xc/0x28
LR is at usb_hcd_fsl_probe+0x2c8/0x44c [ehci_hcd]
pc : [<80062b58>]    lr : [<7f060934>]    psr: a0000013
sp : ba11be80  ip : 00005027  fp : 000a76e0
r10: 00000048  r9 : ba11a000  r8 : bfd4d608
r7 : ffffffed  r6 : bfd4d600  r5 : bfc84400  r4 : 80aaee48
r3 : 80062b4c  r2 : 00000000  r1 : 60000093  r0 : 00000000
Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 10c53c7d  Table: 4a1c404a  DAC: 00000015
Process modprobe (pid: 1555, stack limit = 0xba11a2f0)
Stack: (0xba11be80 to 0xba11c000)
be80: bfd97600 7f060934 00000000 00000000 bfd4d608 bfd4d608 80aca808 bfd4d63c
bea0: 7f062bd4 80041704 ba11a000 00000000 000a76e0 802a5cec bfd4d608 802a4a14
bec0: bfd4d608 7f062bd4 bfd4d63c 00000000 80041704 802a4bac 7f062bd4 ba11bee8
bee0: 802a4b20 802a4254 bffd4040 bff03f38 7f065000 7f062bd4 80a934c8 bfc8cd20
bf00: 00000000 802a3be0 7f062b1c 7f062bd4 00000000 7f017ec8 7f062bd4 00000000
bf20: 7f065000 80041704 00000000 802a51a0 7f017ec8 80aae500 00000000 7f065000
bf40: 80041704 7f065058 000a79e8 8003b4c4 00000000 00000000 00000000 80a14834
bf60: 000a79e8 000a79e8 7f062c20 00000000 0000e67b 80041704 ba11a000 00000000
bf80: 000a76e0 800aa428 ba076740 800f58dc 000a79e8 0000e67b 00000000 000a75d0
bfa0: 00000080 80041580 0000e67b 00000000 000a79e8 0000e67b 000a75d0 000a76e0
bfc0: 0000e67b 00000000 000a75d0 00000080 000a6a78 00000008 000a76a0 000a76e0
bfe0: 7ec7ab50 7ec7ab40 0001a32c 2ace6490 20000010 000a79e8 4fffe821 4fffec21
[<80062b58>] (fsl_usb_host_uninit_ext+0xc/0x28) from [<7f060934>]
	(usb_hcd_fsl_probe+0x2c8/0x44c [ehci_hcd])
[<7f060934>] (usb_hcd_fsl_probe+0x2c8/0x44c [ehci_hcd]) from [<802a5cec>]
	(platform_drv_probe+0x18/0x1c)
[<802a5cec>] (platform_drv_probe+0x18/0x1c) from [<802a4a14>]
	(driver_probe_device+0x98/0x1a4)
[<802a4a14>] (driver_probe_device+0x98/0x1a4) from [<802a4bac>]
	(__driver_attach+0x8c/0x90)
[<802a4bac>] (__driver_attach+0x8c/0x90) from [<802a4254>]
	(bus_for_each_dev+0x60/0x8c)
[<802a4254>] (bus_for_each_dev+0x60/0x8c) from [<802a3be0>]
	(bus_add_driver+0x184/0x25c)
[<802a3be0>] (bus_add_driver+0x184/0x25c) from [<802a51a0>]
	(driver_register+0x78/0x13c)
[<802a51a0>] (driver_register+0x78/0x13c) from [<7f065058>]
	(ehci_hcd_init+0x58/0x88 [ehci_hcd])
[<7f065058>] (ehci_hcd_init+0x58/0x88 [ehci_hcd]) from [<8003b4c4>]
	(do_one_initcall+0x30/0x16c)
[<8003b4c4>] (do_one_initcall+0x30/0x16c) from [<800aa428>]
	(sys_init_module+0x84/0x19c)
[<800aa428>] (sys_init_module+0x84/0x19c) from [<80041580>]
	(ret_fast_syscall+0x0/0x30)
Code: 80aaee48 e92d4010 e30e4e48 e34840aa (e590005c)
---[ end trace 719afdfe4af3a442 ]---

Signed-off-by: Peter Chen <peter.chen@freescale.com>