qrtr: Add FIFO based communication between VMs

Add QRTR communication support between two virtual machines
by using shared FIFO and virtual IRQs.

Change-Id: I8fd2115a6ad5acd9a6dac2fa511860a8a68c16ee
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>