packages: nvram: add NVRAM quirks for bcm53xx target

Add NVRAM quirks script for the bcm53xx target. Split NVRAM quirks for the
bcm47xx and bcm53xx targets. Move clear partialboot NVRAM quirk for Linksys
EA9500 here. Add set wireless LED behaviour quirk for Asus RT-AC88U.

Use boot() instead of start() as nvram commands are meant to be executed
only once, at boot.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
(cherry picked from commit f4e219fd5e)

target/linux/bcm53xx/base-files/etc/init.d/clear_partialboot

@@ -1,13 +0,0 @@
-#!/bin/sh /etc/rc.common
-
-START=97
-boot() {
-	. /lib/functions.sh
-
-	case $(board_name) in
-		linksys,panamera)
-			# clear partialboots
-			nvram set partialboots=0 && nvram commit
-			;;
-	esac
-}