Address handles (AH) are a limited HW resource and some user applications
may create large numbers of identical AH's.  Avoid running out of AH's by
reusing existing identical ones.

Link: https://lore.kernel.org/r/20220228183650.290-1-shiraz.saleem@intel.comSigned-off-by: Mustafa Ismail <mustafa.ismail@intel.com>
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>