fs/yaffs2/yaffs_guts.c: Fix some GCC 4.6 warnings

Fix:
yaffs_guts.c: In function 'yaffs_CheckChunkErased':
yaffs_guts.c:854:6: warning: variable 'result' set but not used
yaffs_guts.c: In function 'yaffs_UpdateObjectHeader':
yaffs_guts.c:3463:6: warning: variable 'result' set but not used
yaffs_guts.c: In function 'yaffs_GrabChunkCache':
yaffs_guts.c:3774:6: warning: variable 'pushout' set but not used
yaffs_guts.c: In function 'yaffs_Scan':
yaffs_guts.c:5237:6: warning: variable 'result' set but not used
yaffs_guts.c: In function 'yaffs_CheckObjectDetailsLoaded':
yaffs_guts.c:5748:6: warning: variable 'alloc_failed' set but not used
yaffs_guts.c:5747:6: warning: variable 'result' set but not used
yaffs_guts.c: In function 'yaffs_ScanBackwards':
yaffs_guts.c:5808:6: warning: variable 'deleted' set but not used
yaffs_guts.c:5806:6: warning: variable 'result' set but not used
yaffs_guts.c: In function 'yaffs_GetObjectName':
yaffs_guts.c:6657:7: warning: variable 'result' set but not used
[-Wunused-but-set-variable]

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