package/rpi-firmware: bump for misc fixes and improvements

This fixes a few shortcomings in the boot firmware:
  - emmc pll clock issues
  - audio underruns and chirps
  - unload of sensor drivers (?)
  - missing config.txt no longer borks the boot
  - lockups during long exposures on the camera
  - YUV-to-texture fastpath for the camera

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rpi-firmware/rpi-firmware.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-RPI_FIRMWARE_VERSION = 18a163f9341755b00841312af2878afeb64c131c
+RPI_FIRMWARE_VERSION = f7e9bcd25c9b01521fdf88aac2740b6cfc887dfb
 RPI_FIRMWARE_SITE = http://github.com/raspberrypi/firmware/tarball/$(RPI_FIRMWARE_VERSION)
 RPI_FIRMWARE_LICENSE = BSD-3c
 RPI_FIRMWARE_LICENSE_FILES = boot/LICENCE.broadcom