drm/i915/hdcp: Add encoder check in intel_hdcp_get_capability

Sometimes during hotplug scenario or suspend/resume scenario encoder is
not always initialized when intel_hdcp_get_capability add
a check to avoid kernel null pointer dereference.
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Dnyaneshwar Bhadane <dnyaneshwar.bhadane@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240722064451.3610512-2-suraj.kandpal@intel.com

drivers/gpu/drm/i915/display/intel_hdcp.c

@@ -203,11 +203,16 @@ int intel_hdcp_read_valid_bksv(struct intel_digital_port *dig_port,
 /* Is HDCP1.4 capable on Platform and Sink */
 bool intel_hdcp_get_capability(struct intel_connector *connector)
 {
-	struct intel_digital_port *dig_port = intel_attached_dig_port(connector);
+	struct intel_digital_port *dig_port;
 	const struct intel_hdcp_shim *shim = connector->hdcp.shim;
 	bool capable = false;
 	u8 bksv[5];
 
+	if (!intel_attached_encoder(connector))
+		return capable;
+
+	dig_port = intel_attached_dig_port(connector);
+
 	if (!shim)
 		return capable;