metadump: make non-local function variables more obvious

metadump: make non-local function variables more obvious

In _xfs_verify_metadump_v2(), we want to set up some loop devices,
record the names of those loop devices, and then leave the variables in
the global namespace so that _xfs_cleanup_verify_metadump can dispose of
them.

Elsewhere in fstests the convention for global variables is to put them
in all caps to make it obvious that they're global and not local
variables, so do that here too.

Cc: <fstests@vger.kernel.org> # v2024.12.08
Fixes: ce79de11337e38 ("fstests: clean up loop device instantiation")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>