ext2: fix a typo on comment in ext2/inode.c

'excpet' should be 'except'.
'ext3_get_branch' should be 'ext2_get_branch'.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>