DefaultMediaTheme: fix Slider scale

Values are using a scale of 1000, but limits are set 0..100. Very
visible in media preferencies when using balance controls for stereo
connections in the mixer: the control is shown full right at first and
the moment you touch it and the gain is updated, you only get sound from
the left channel.

Probably the root cause of #15836 and #16070.

Change-Id: I31d3b6b11a57ca99a1cc8373d9fb003f21b192b3
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3445
Reviewed-by: Adrien Destugues <[email protected]>

src/kits/media/DefaultMediaTheme.cpp

@@ -884,7 +884,8 @@ DefaultMediaTheme::MakeViewFor(BParameter *parameter)
 			}
 
 			BSlider *slider = new Slider(parameter->Name(),
-				parameter->Name(), 0, 100, continuous);
+				parameter->Name(), int32(continuous.MinValue() * 1000),
+				int32(continuous.MaxValue() * 1000), continuous);
 
 			return slider;
 		}