xfs: refactor hint based zone allocation

xfs: refactor hint based zone allocation

Replace the co-location code with a matrix that makes it more clear
on how the decisions are made.

The matrix contains scores for zone/file hint combinations. A "GOOD"
score for an open zone will result in immediate co-location while "OK"
combinations will only be picked if we cannot open a new zone.

Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>