Change the temp map to ROM to align addresses to page size.

Change the temp map to ROM to align addresses to page size.

With a page size of BOOKE_PAGESZ_16M, both the real and effective
addresses must be multiples of 16MB.  The hardware silently truncates
them so the code happens to work.  This patch clarifies the situation
by establishing addresses that the hardware doesn't need to truncate.

Signed-off-by: Andrew Klossner <andrew@cesa.opbu.xerox.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>