package/rpi-firmware: bump version

Misc enhancements and fixes all over the place, most notably:
 - FW: better overclocking, add Mediatek mt7601u Wi-Fi driver, bump
       kernel version to 4.1.5...
 - DT: fix SPI, I²S, gpio-poweroff, add MCP7941X, uart1, Fen Logic
       VGA666 board, RPi Sense HAT...
 - video: add early frame sequential 3D support, YUV_UV destination
          format, qpu deinterlace...

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>