RDMA/nes: Enhanced PFT management scheme

Change management of perfect filter table to allow enhanced
performance applications.

Signed-off-by: Vadim Makhervaks <vmakhervaks@neteffect.com>
Signed-off-by: Sweta Bhatt <sweta.bhatt@einfochips.com>
Signed-off-by: Chien Tung <ctung@neteffect.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>