board/mousse/flash.c: Fix GCC 4.6 buil warnings

Fix:
flash.c: In function 'flash_erase':
flash.c:780:18: warning: variable 'l_sect' set but not used
[-Wunused-but-set-variable]
flash.c:779:11: warning: variable 'addr' set but not used
[-Wunused-but-set-variable]

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