ext3: Return -EINVAL when start is beyond the end of fs in ext3_trim_fs()

We should return -EINVAL when the FITRIM parameters are not sane, but
currently we are exiting silently if start is beyond the end of the
file system. This commit fixes this so we return -EINVAL as other file
systems do.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
CC: Jan Kara <jack@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>