board/evb64260/sdram_init.c: Fix GCC 4.6 build warnings

Fix:
sdram_init.c: In function 'setup_sdram_common':
sdram_init.c:333:49: warning: variable 'ecc' set but not used
[-Wunused-but-set-variable]
sdram_init.c: In function 'setup_sdram':
sdram_init.c:410:13: warning: variable 'check' set but not used
[-Wunused-but-set-variable]

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