linux-raspberrypi: Update kernel to 3.12.21

Amongst other patches, this release includes a fix to an issue with
gstreamer1.0 and v4l2src blocking

ref: https://bugzilla.gnome.org/show_bug.cgi?id=726521

ref: http://tinyurl.com/mkqooeg

To make use of the optional fix the module parameter gst_v4l2src_is_broken
needs to be set when loading bcm2835-v4l2.ko

With this in place, and with userland and gstreamer1.0-omx patches,
gstreamer1.0 can be used with PiCam via v4l2src instead of raspivid.

(There may still be performance issues to be addressed for v4l2src vs
raspivid pipe & fdsrc).

Change-Id: Ia0ed4e6c8f27df9bb12ae2350526f6314e016d51
Signed-off-by: Alex J Lennon <ajlennon@dynamicdevices.co.uk>
pi-blaster: Added recipe

This project enables PWM on the GPIO pins you request of a Raspberry Pi.
The technique used is extremely efficient: does not use the CPU and gives
very stable pulses

Patches have been provided to build pi-blaster using autotools, and to
remove startup script dependencies on the lsb.

Change-Id: Ie1bec0702e4520d24e4f024aafff14ddef825589
Signed-off-by: Alex J Lennon <ajlennon@dynamicdevices.co.uk>
Merge "pi-blaster: Added recipe"
Merge "linux-raspberrypi: Update kernel to 3.12.21"
README: Add patch guidelines info

Change-Id: I2dac882a6dbe2fbca63a5c7405339edcca18cf04
Signed-off-by: Andrei Gherzan <andrei@gherzan.ro>