brcm2708: update linux 4.9 patches to latest version

As usual these patches were extracted and rebased from the raspberry pi repo:
https://github.com/raspberrypi/linux/tree/rpi-4.9.y

- Remove led1 from diag.sh for RPi3 since it causes boot issues.
- Fix modules.mk typos.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

target/linux/brcm2708/patches-4.9/0020-firmware-Updated-mailbox-header.patch

@@ -1,4 +1,4 @@
-From 05f9e93200ec5d5e27c8a93f69588180cddda924 Mon Sep 17 00:00:00 2001
+From e4edca57f8db4d03ad4dc82dd6761c0142ab310d Mon Sep 17 00:00:00 2001
 From: popcornmix <popcornmix@gmail.com>
 Date: Mon, 25 Jan 2016 17:25:12 +0000
 Subject: [PATCH] firmware: Updated mailbox header