bnxt_re: changing the ip address shouldn't affect new connections

While adding a new gid, the driver currently does not return the context
back to the stack. A subsequent del_gid() (e.g, when ip address is changed)
doesn't find the right context in the driver and it ends up dropping that
request. This results in the HW caching a stale gid entry and traffic fails
because of that. Fix by returning the proper context in bnxt_re_add_gid().

Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>