HDCP: add getCaps to query HDCP module capabilities

This is used now to query whether HDCP module supports encryption
from a native buffer output from the encoder.

Bug: 10609422

Change-Id: Ib7fa14e7f4de1da90b46eaa174a7a05ec9dacbdc

include/media/hardware/HDCPAPI.h

@@ -88,6 +88,11 @@ struct HDCPModule {
     // Request to shutdown the active HDCP session.
     virtual status_t shutdownAsync() = 0;
 
+    // Returns the capability bitmask of this HDCP session.
+    virtual uint32_t getCaps() {
+        return HDCP_CAPS_ENCRYPT;
+    }
+
     // ENCRYPTION only:
     // Encrypt data according to the HDCP spec. "size" bytes of data are
     // available at "inData" (virtual address), "size" may not be a multiple