firmware: qcom: scm: Add HDCP Support

HDCP driver needs to check if secure environment supports HDCP.  If it's
supported, then it requires to program some registers through SCM.
Add qcom_scm_hdcp_available and qcom_scm_hdcp_req to support these
requirements.

Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>