[forcedeth] Never change the NVREG_TRANSMITPOLL_MAC_ADDR_REV flag

iPXE operates the forcedeth NIC in promiscuous mode, and never changes
the unicast MAC address filter registers.  We should not therefore set
the flag indicating (to other drivers loaded later) that the MAC
address order has already been corrected.

Reported-by: Tal Aloni <tal.aloni.il@gmail.com>
Tested-by: Tal Aloni <tal.aloni.il@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/forcedeth.c

 		dev->hw_addr[3] = ( orig_mac[0] >> 16 ) & 0xff;
 		dev->hw_addr[4] = ( orig_mac[0] >> 8 ) & 0xff;
 		dev->hw_addr[5] = ( orig_mac[0] >> 0 ) & 0xff;
-
-		writel ( txreg | NVREG_TRANSMITPOLL_MAC_ADDR_REV,
-			 ioaddr + NvRegTransmitPoll );
-
-		DBG ( "set workaround bit for reversed mac addr\n" );
 	}
 
 	if ( ! is_valid_ether_addr ( dev->hw_addr ) )