r8169: enforce RX_MULTI_EN on rtl8168ep/8111ep chips

Enforcing this flag in RxConfig for the mentioned chips fixes netdev
watchdog issues prepended with AMD IOMMU message(s) like:
AMD-Vi: Event logged [IO_PAGE_FAULT device=01:00.0 domain=0x001d address=0x0000000000003000 flags=0x0050]

Note that this flag is also set in Realtek's own driver for these chips.
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Tested-by: Alexander Lindqvist <alexander@bitspace.se>
Acked-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169.c

@@ -4875,10 +4875,12 @@ static void rtl_init_rxcfg(struct rtl8169_private *tp)
 	case RTL_GIGA_MAC_VER_46:
 	case RTL_GIGA_MAC_VER_47:
 	case RTL_GIGA_MAC_VER_48:
+		RTL_W32(RxConfig, RX128_INT_EN | RX_DMA_BURST | RX_EARLY_OFF);
+		break;
 	case RTL_GIGA_MAC_VER_49:
 	case RTL_GIGA_MAC_VER_50:
 	case RTL_GIGA_MAC_VER_51:
-		RTL_W32(RxConfig, RX128_INT_EN | RX_DMA_BURST | RX_EARLY_OFF);
+		RTL_W32(RxConfig, RX128_INT_EN | RX_MULTI_EN | RX_DMA_BURST | RX_EARLY_OFF);
 		break;
 	default:
 		RTL_W32(RxConfig, RX128_INT_EN | RX_DMA_BURST);