xfs: fix quota accounting when a mount is idmapped

Nowadays, we indirectly use the idmap-aware helper functions in the VFS
to set the initial uid and gid of a file being created.  Unfortunately,
we didn't convert the quota code, which means we attach the wrong dquots
to files created on an idmapped mount.

Fixes: f736d93d ("xfs: support idmapped mounts")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>