misc: fix $MKFS_PROG.$FSTYP usage treewide

misc: fix $MKFS_PROG.$FSTYP usage treewide

Replace all the $MKFS_PROG.$FSTYP invocations with $MKFS_PROG -t $FSTYP.
The mkfs wrapper binary knows how to search the user's $PATH to find the
appropriate mkfs delegate, which the author uses to switch between
development and distro versions of various tools.

Unfortunately, using "$MKFS_PROG.$FSTYP" means that the shell only looks
in the same directory as the mkfs wrapper, which means that we can end
up mixing different tool versions when this is the case.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>