User space should receive the maximum edpm size from kernel driver,
similar to other edpm/ldpm related limits.  Add an additional parameter to
the alloc_ucontext_resp structure for the edpm maximum size.

In addition, pass an indication from user-space to kernel
(and not just kernel to user) that the DPM sizes are supported.

This is for supporting backward-forward compatibility between driver and
lib for everything related to DPM transaction and limit sizes.

This should have been part of commit mentioned in Fixes tag.

Link: https://lore.kernel.org/r/20200707063100.3811-3-michal.kalderon@marvell.com
Fixes: 93a3d05f ("RDMA/qedr: Add kernel capability flags for dpm enabled mode")
Signed-off-by: Ariel Elior <ariel.elior@marvell.com>
Signed-off-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>