generic/699: fix failure with MOUNT_OPTIONS

generic/699: fix failure with MOUNT_OPTIONS

generic/699 uses overalyfs helper _overlay_mount_dirs, which is meant to
be used by overlayfs tests, where MOUNT_OPTIONS refer to overalyfs mount
options.

Using this helper from a generic test when FSTYP is not overlay is
causing undesired results. For example, when MOUNT_OPTIONS is defined
and includes a mount option not supported by overalyfs (e.g. 'acl'),
the test is notrun because of:

mount: /vdc/ovl-merge: fsconfig() failed: overlay: Unknown parameter 'acl'.

There is no other generic test that includes the common/overlay helpers
and uses them, so remove this practice from generic/699 as well.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>