Add sdxpinn modem documentation for qcom remoteproc. commit 523b0d5e8899 ("dt-bindings: Add documentation for sdxpinn modem"). Change-Id: I5e196b51e69cd6c7ec1af01bda1c460c9ce5160a Signed-off-by: Khaja Hussain Shaik Khaji <quic_kshaikkh@quicinc.com>