bluetooth: bring back the stock BROADCOM bluesleep implementation.

The LG implementation lacks two proc files that are causing errors in userland:
lpm and btwrite, this commit brings these back and aligns the rest of the functions
with the stock implementation from CodeAurora.

Change-Id: Ia0bb7b070fa59851c036917ec61b8046494c40d6
board-gk: re-enable BT GPIO PINS and make rfkill0 use them to power
the bluetooth device

Change-Id: I465cc5d5491e5ba4a81b4f297468dca211020a78