xfs: report realtime block quota limits on realtime directories

[ Upstream commit 9a17ebfea9d0c7e0bb7409dcf655bf982a5d6e52 ]

On the data device, calling statvfs on a projinherit directory results
in the block and avail counts being curtailed to the project quota block
limits, if any are set.  Do the same for realtime files or directories,
only use the project quota rt block limits.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Stable-dep-of: 4b8d867ca6e2 ("xfs: don't over-report free space or inodes in statvfs")
Signed-off-by: Sasha Levin <sashal@kernel.org>