rockchip: reliably distribute net interrupts

On the NanoPI R4S it takes an average of 3..5 seconds for the network devices
to appear in '/proc/interrupts'.
Wait up to 10 seconds to ensure that the distribution of the interrupts
really happens.

Signed-off-by: Ronny Kotzschmar <ro.ok@me.com>
(cherry picked from commit 9b00e97956)

target/linux/rockchip/armv8/base-files/etc/hotplug.d/net/40-net-smp-affinity

@@ -4,8 +4,15 @@
 
 get_device_irq() {
 	local device="$1"
+	local line
+	local seconds="0"
 
-	local line=$(grep -m 1 "${device}\$" /proc/interrupts)
+	# wait up to 10 seconds for the irq/device to appear
+	while [ "${seconds}" -le 10 ]; do
+		line=$(grep -m 1 "${device}\$" /proc/interrupts) && break
+		seconds="$(( seconds + 2 ))"
+		sleep 2
+	done
 	echo ${line} | sed 's/:.*//'
 }