ramips: move set-irq-affinity script to mt7621 subtarget

Move the set-irq-affinity script to mt7621 because it is the only
SMP subtarget.

Signed-off-by: DENG Qingfang <dengqf6@mail2.sysu.edu.cn>

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

@@ -1,31 +0,0 @@
-#!/bin/sh /etc/rc.common
-
-START=99
-
-get_irq() {
-	local name="$1"
-	grep -m 1 "$name" /proc/interrupts | cut -d: -f1 | sed 's, *,,'
-}
-
-set_irq_affinity() {
-	local name="$1"
-	local val="$2"
-	local irq="$(get_irq "$name")"
-	[ -n "$irq" ] || return
-	echo "$val" > "/proc/irq/$irq/smp_affinity"
-}
-
-start() {
-	if grep -q 'processor.*: 2' /proc/cpuinfo; then
-		mask1=4
-		mask2=8
-	elif grep -q 'processor.*: 1' /proc/cpuinfo; then
-		mask1=2
-		mask2=2
-	else
-		return
-	fi
-
-	set_irq_affinity mt76x2e $mask1
-	set_irq_affinity mt7603e $mask2
-}