be2net: set interrupt moderation for Skyhawk-R using EQ-DB

Currently adaptive interrupt moderation is set by calculating
and configuring an EQ-delay every second. This is done via
a FW-cmd. But, on Skyhawk-R a "re-arm to interrupt" delay
can be set while ringing the EQ-DB. This patch uses this
facility to calculate and set the interrupt delay every 1ms.
This helps moderating interrupts better when the traffic
is bursty.

Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@avagotech.com>
Signed-off-by: Sathya Perla <sathya.perla@avagotech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>