slatecom-events-bridge: Add driver for events from Slate

Add driver to send and receive events from Slate
co-processor. The driver uses Glink channel to communicate
with Slate.

Change-Id: I2b7cf9a47e8947f79c7e9cd8b1311ff8c04bf848
Signed-off-by: Ajit Kumar <kajit@codeaurora.org>