enic: Add support for PORT_REQUEST_PREASSOCIATE_RR

Current enic code only supports ASSOCIATE and DISASSOCIATE port profile
operations. This patch adds enic support for port profile
PORT_REQUEST_PREASSOCIATE_RR operation. The VIC adapter (8021qbh) is capable
of handling port profile requests done in two steps namely PREASSOCIATE_RR
and ASSOCIATE today. The motivation to support PREASSOCIATE_RR comes mainly
from its use as an optimization during VM migration ie, to do resource
reservation on destination host before resources on source host are released.

PREASSOCIATE_RR is a VDP operation and according to the latest at IEEE,
8021qbh will also need to support VDP commands.

In addition to handling the new PORT_REQUEST_PREASSOCIATE_RR operation
this patch also does the below:
- Introduces handlers for PORT_REQUEST operations
- Moves most of the port profile handling code to new files enic_pp.[ch]
- Uses new fw devcmds for port profile operations

Signed-off-by: Roopa Prabhu <roprabhu@cisco.com>
Signed-off-by: David Wang <dwang2@cisco.com>
Signed-off-by: Christian Benvenuti <benve@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>