xfs: switch xfs_get_defquota to take explicit type

xfs_get_defquota() currently takes an xfs_dquot, and from that obtains
the type of default quota we should get (user/group/project).

But early in init, we don't have access to a fully set up quota, so
that's not possible.  The next patch needs go set up default quota
timers early, so switch xfs_get_defquota to take an explicit type
and add a helper function to obtain that type from an xfs_dquot
for the existing callers.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>