[PATCH] SDLA firmware upgrade should require CAP_SYS_RAWIO (not just CAP_NET_ADMIN)

There were a few variants on the list trying to work out what the valid
ranges to verify for write are but they sort of missed the point, if you
can load new firmware you can have fun anyway.

drivers/net/wan/sdla.c

@@ -1306,6 +1306,8 @@ NOTE:  This is rather a useless action right now, as the
 
 		case SDLA_WRITEMEM:
 		case SDLA_READMEM:
+			if(!capable(CAP_SYS_RAWIO))
+				return -EPERM;
 			return(sdla_xfer(dev, ifr->ifr_data, cmd == SDLA_READMEM));
 
 		case SDLA_START: