board/lwmon/pcmcia.c: Fix GCC 4.6 build warnings

board/lwmon/pcmcia.c: Fix GCC 4.6 build warnings

Fix:
pcmcia.c: In function 'pcmcia_hardware_enable':
pcmcia.c:33:21: warning: variable 'cp' set but not used
[-Wunused-but-set-variable]
pcmcia.c:32:20: warning: variable 'immap' set but not used
[-Wunused-but-set-variable]
pcmcia.c: In function 'pcmcia_voltage_set':
pcmcia.c:174:20: warning: variable 'immap' set but not used
[-Wunused-but-set-variable]

Signed-off-by: Wolfgang Denk <wd@denx.de>