dt-bindings: soc: qcom: Add dt-bindings for the IPCC test driver

The dt-bindings describes the self-ping test that it conducts
and all the properties that are required to configure the
test driver's DT node.

Change-Id: I3e4b3dd0ef32f6c05ca566ecdb062799f448addf
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>