kernel: bump to 3.10.38

kernel: config: Add CONFIG_NFS_SWAP
See: https://github.com/raspberrypi/firmware/issues/266

firmware: alsa: fix for wrong volume when starting playback
See: https://github.com/raspberrypi/linux/issues/570

firmware: Support passthrough through alsa with channels=0
See: https://github.com/raspberrypi/linux/issues/528