fstests: add some missing _require_loop's

Got a new box running overnight fstests and noticed a couple of failures
because I forgot to enable loop device support.  Fix these two tests to
have _require_loop so they don't fail if there's no loop device support.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Zorro Lang <zlang@kernel.org>