RDMA/nldev: Add command to set pinned FRMR handles

RDMA/nldev: Add command to set pinned FRMR handles

Allow users to set through netlink, for a specific FRMR pool, the amount
of handles that are not aged, and fill the pool to this amount.

This allows users to warm-up the FRMR pools to an expected amount of
handles with specific attributes that fits their expected usage.

Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Reviewed-by: Patrisious Haddad <phaddad@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
Link: https://patch.msgid.link/20260226-frmr_pools-v4-10-95360b54f15e@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>