qlcnic: Collect firmware dump using DMA on 82xx adapters

o Add support to collect RDMEM section of firmware dump
  using PEX DMA method.
o This patch uses most of the code used for PEX DMA support
  on 83xx series adapters and some refactoring.

Signed-off-by: Shahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>