kernel: Bump to 3.12.26

kernel: Added support for HiFiBerry DAC+
See: https://github.com/raspberrypi/linux/pull/657

kernel: ASoC: BCM: Typo in RPi-DAC driver
See: https://github.com/raspberrypi/linux/pull/656

kernel: bcm2708_fb : Implement the FBIOBLANK ioctl using the mailbox property
See: https://github.com/raspberrypi/linux/pull/655

firmware: vmcs_host: Fix missing install of libvcilcs.so
See: https://github.com/raspberrypi/userland/pull/194

userland: Update of RaspiStillYUV.c and burst mode
See: https://github.com/raspberrypi/userland/pull/191

firmware: Add burst mode to raspistill/raspiyuv and settings and long exposure to raspivid
Set burst mode before first capture and force dynamic frame rate to fulfil shutter speed requirement.
MMAL: Correct parameter names for denoise control
H264 encode: Sort inline headers for VBR.
Implements vc_image_fill for VC_IMAGE_YUV_UV images
Add vc_image_atext support for YUV_UV images
ncrease memory reservation for annotate stage
Add annotate stage to Raspberry Pi Full variant. Allow config
Add control of the annotate stage to the debug tuner
Add YUV_UV support to Camplus annotate stage
Add AF metadata before postproc stage,Refactor annotate plots
Add lens position plot to annotate state.Add frame no. Tidy up code a bit.
MJPEG: Rework so that it can have a 4MB output FIFO
OV5647: Tidy up unused tuning data
AGC: If gain/threshold are 0, initialise them
Pull latest vcos_msgqueue from vc4/DEV
OV5647: Fix for incorrectly selecting 0.16-1fps mode
See: http://www.raspberrypi.org/forums/viewtopic.php?f=43&t=83353