dt-bindings: remoteproc: Add OMAP remoteproc bindings

Add the device tree bindings document for the IPU and DSP
remote processor devices on OMAP4+ SoCs.

Cc: Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Suman Anna <s-anna@ti.com>
[t-kristo@ti.com: converted to schema]
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200324110035.29907-2-t-kristo@ti.comSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>