Major BeagleLogic code refactor

 * Data structures and buffer handling improved
 * Code ready to be migrated out of pru_rproc_bl.c

Signed-off-by: Kumar Abhishek <abhishek@theembeddedkitchen.net>
Kernel Module migration stage1:Cleanup beaglelogic.c

Signed-off-by: Kumar Abhishek <abhishek@theembeddedkitchen.net>
Kernel Module migration stage2:Fill beaglelogic.c

 * Implement inter-module communication through
   a few functions imported from the pru_rproc module
   abstracted of all the pru_rproc data structures,
   and export an IRQ handler from the private data
 * Add a glue header file to export the needed attributes
   and functions to our module
 * TODO: Implement data reading from the device tree

Signed-off-by: Kumar Abhishek <abhishek@theembeddedkitchen.net>
Kernel module migration: Cleanup pru_rproc_bl.c

The code in pru_rproc_bl.c is now fully independent of
the beaglelogic module.
Add link functions to beaglelogic module

Signed-off-by: Kumar Abhishek <abhishek@theembeddedkitchen.net>
Kernel Module: Update device tree overlay file

Signed-off-by: Kumar Abhishek <abhishek@theembeddedkitchen.net>