rpi-firmware: bump version

This commit bumps the rpi-firmware to a more recent version that
includes support for the Raspberry Pi 3.

Signed-off-by: Ubaldo Porcheddu <ubaldo@eja.it>
[Thomas: tweak commit log.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/rpi-firmware/rpi-firmware.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-RPI_FIRMWARE_VERSION = 8b4e5482b52e6fb438dddc0d88ba0ba8d44af54b
+RPI_FIRMWARE_VERSION = 951799bbcd795ddf27769d14acf4813fdcbe53dc
 RPI_FIRMWARE_SITE = $(call github,raspberrypi,firmware,$(RPI_FIRMWARE_VERSION))
 RPI_FIRMWARE_LICENSE = BSD-3c
 RPI_FIRMWARE_LICENSE_FILES = boot/LICENCE.broadcom