xfs: support zone gaps

xfs: support zone gaps

Source kernel commit: 97c69ba1c08d5a2bb3cacecae685b63e20e4d485

Zoned devices can have gaps beyond the usable capacity of a zone and the
end in the LBA/daddr address space.  In other words, the hardware
equivalent to the RT groups already takes care of the power of 2
alignment for us.  In this case the sparse FSB/RTB address space maps 1:1
to the device address space.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>