board/ti/omap1610inn/flash.c: Fix GCC 4.6 build warnings

Fix:
flash.c: In function 'flash_get_offsets':
flash.c:139:10: warning: variable 'pOrgDef' set but not used
[-Wunused-but-set-variable]
flash.c: In function 'flash_erase':
flash.c:280:6: warning: variable 'flag' set but not used
[-Wunused-but-set-variable]
flash.c: In function 'write_data':
flash.c:456:6: warning: variable 'flag' set but not used
[-Wunused-but-set-variable]

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: Tom Rini <trini@ti.com>