board/icu862/pcmcia.c: Fix GCC 4.6 build warning

board/icu862/pcmcia.c: Fix GCC 4.6 build warning

Fix:
pcmcia.c: In function 'cfg_port_B':
pcmcia.c:21:20: warning: variable 'immap' set but not used
[-Wunused-but-set-variable]
pcmcia.c: In function 'pcmcia_hardware_enable':
pcmcia.c:50:20: warning: variable 'immap' set but not used
[-Wunused-but-set-variable]
pcmcia.c: In function 'pcmcia_voltage_set':
pcmcia.c:191:20: warning: variable 'immap' set but not used
[-Wunused-but-set-variable]

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