f2fs/021: test quota mount option

f2fs/021: test quota mount option

This testcase tries to check whether f2fs can handle "usrjquota="
during remount correctly, it expects kernel will encounter NULL
pointer dereference bug w/o the fix ("f2fs: fix to avoid NULL pointer
dereference in f2fs_check_quota_consistency()").

Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Zorro Lang <zlang@kernel.org>