board/mx1ads/syncflash.c: Fix GCC 4.6 warnings

board/mx1ads/syncflash.c: Fix GCC 4.6 warnings

Fix:
syncflash.c: In function 'SF_SR':
syncflash.c:60:10: warning: variable 'tmp1' set but not used
[-Wunused-but-set-variable]
syncflash.c: In function 'SF_PrechargeAll':
syncflash.c:96:6: warning: variable 'tmp' set but not used
[-Wunused-but-set-variable]
mx1ads.c: In function 'board_early_init_f':
mx1ads.c:83:24: warning: variable 'tmp' set but not used
[-Wunused-but-set-variable]
syncflash.c: In function 'SF_Erase':
syncflash.c:112:6: warning: variable 'tmp' set but not used
[-Wunused-but-set-variable]
syncflash.c: In function 'flash_init':
syncflash.c:155:6: warning: variable 'tmp' set but not used
[-Wunused-but-set-variable]

Signed-off-by: Anatolij Gustschin <agust@denx.de>