dt-bindings: net: qrtr: Add FIFO transport bindings

The QRTR FIFO driver acts as a transport driver between virtual
machines for the QRTR core logic. Document the bindings for the shared
memory region and interrupt resources.

Change-Id: Ibdbc9187eec508c9b70b113a0ef222b3e4cf5129
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Chris Lew <clew@codeaurora.org>