qlge: Add support for getting/setting port config.

This patch adds functionality to get and set port parameters.
Currently it is used to set maximum TX/RX frame sizes. This process is
also capable of setting:
1) Pause type: Standard or Priority based.
2) Loop back mode.
3) Enable Jumbo frame mode (included here...)

Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>