nic/pc: disable IRQ coalescing in R8169 driver

This commit patches the DDE Linux contrib code to remove IRQ coalescing
from the R8169 driver that for reason not yet known leads to interrupts
occurring irregularly.

Issue #5356.

repos/dde_linux/patches/r8169_disable_irq_coalescing.patch

@@ -0,0 +1,15 @@
+Disable IRQ coalescing as it seems to not work properly in our
+port because at some point triggering interrupts stops altogether.
+In this case the netperf tests produce around 0.1(!) MBit/s of
+throughput.
+--- src/linux/drivers/net/ethernet/realtek/r8169_main.c
++++ src/linux/drivers/net/ethernet/realtek/r8169_main.c
+@@ -5374,7 +5374,7 @@
+ 	dev->hw_features |= NETIF_F_RXALL;
+ 	dev->hw_features |= NETIF_F_RXFCS;
+ 
+-	netdev_sw_irq_coalesce_default_on(dev);
++	// netdev_sw_irq_coalesce_default_on(dev);
+ 
+ 	/* configure chip for default features */
+ 	rtl8169_set_features(dev, dev->features);

repos/dde_linux/ports/linux.hash

@@ -1 +1 @@
-403e8fecb5e0303605e2c7b913089710e66ad3d6
+501de7d0dc5363c9f271c2cd853b963b2a881438

repos/dde_linux/ports/linux.port

@@ -18,6 +18,7 @@ PATCH_FILES := i915_irq.patch \
                usb_net_cdc_ncm.patch \
                usb_net_pinephone.patch \
                usb_net_smsc95xx.patch \
-               workqueue_deadlock.patch
+               workqueue_deadlock.patch \
+               r8169_disable_irq_coalescing.patch
 
 PATCHES += $(addprefix patches/,$(PATCH_FILES))