libcamera: Use simpler Signal::disconnect() function

When disconnecting a signal from a receiver, it is usually not necessary
to specify the receiver's slot function explicitly, as the signal is
often connected to a single slot for a given receiver. We can thus use a
simpler version of Signal::disconnect() that takes a pointer to the
receiver object only. This reduces code size, as the disconnect()
function is a template function.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

test/camera/camera_reconfigure.cpp

@@ -130,7 +130,7 @@ private:
 			return TestFail;
 		}
 
-		camera_->requestCompleted.disconnect(this, &CameraReconfigure::requestComplete);
+		camera_->requestCompleted.disconnect(this);
 
 		requests_.clear();