f2fs/{022,023}: clear MOUNT_OPTIONS alongside MKFS_OPTIONS

f2fs/{022,023}: clear MOUNT_OPTIONS alongside MKFS_OPTIONS

Currently, f2fs/022 and f2fs/023 only clears MKFS_OPTIONS. This causes
the tests to fail when leftover MOUNT_OPTIONS depend on unapplied
MKFS_OPTIONS. So MOUNT_OPTIONS should also be cleared to ensure reliable
mounting.

Signed-off-by: Joanne Chang <joannechien@google.com>
Reviewed-by: Zorro Lang <zlang@kernel.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Zorro Lang <zlang@kernel.org>