Staging: sxg: Read the correct MAC address from the card for Rev B cards

Read the correct MAC address from EEPROM/Flash.
Without this fix, all the interfaces were using the same MAC address.
This works on Rev B firmware.

Signed-off-by: Christopher Harrer <charrer@alacritech.com>
Signed-off-by: Mithlesh Thukral <mithlesh@linsyssoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>