ramips: mt7621: remove set-affinity script

From https://github.com/openwrt/openwrt/pull/12280#issuecomment-1489279860
On Ethernet and WLAN, NAPI is threaded for all queues. This means that the
processing work is not stuck on the CPU that fired the IRQ. Under heavy
load, IRQs get disabled anyway, so it should not matter at all which CPUs
the IRQs fire on.

Basic testing indicates this to be true. There's no speedup or slowdown.

Signed-off-by: Rosen Penev <[email protected]>

target/linux/ramips/mt7621/base-files/etc/init.d/set-irq-affinity

@@ -1,19 +0,0 @@
-#!/bin/sh /etc/rc.common
-
-START=99
-
-start() {
-	if grep -q 'processor.*: 2' /proc/cpuinfo; then
-		mask=4
-	elif grep -q 'processor.*: 1' /proc/cpuinfo; then
-		mask=2
-	else
-		return
-	fi
-
-	for irq in $(grep "mt76..e" /proc/interrupts | cut -d: -f1 | sed 's, *,,')
-	do
-		echo "$mask" > "/proc/irq/$irq/smp_affinity"
-		[ $mask = 4 ] && mask=8
-	done
-}