soc: qcom: Add BG PIL and feature drivers for msm8909w

BG is a companion chip for msm8909 for low power needs.
Add BG PIL driver to provide load, subsystem restart
and ramdump collection support.

The driver loads the BG firmware into memory and sends
a command to the secure userspace application to initiate
secure transfer of the BG firmware into internal memory
of BG and reset BG. The subsystem restart depends on four
GPIOs present between MSM8909 and BG.

Snapshot of BG PIL and feature drivers taken from msm-3.18
kernel version@ commit 5554caa9f538fe ("soc: qcom: Add 
Blackghost(BG) chip PIL driver")

Change-Id: Ica6fa7a7df94a869ff09a1697ea04ee65afbd501
Signed-off-by: Ramesh Yadav Javadi <javadi@codeaurora.org>