libobs: Use limited range for R10l output

DeckLink hardware seems to want the values in video range.

Author: jpark37

libobs/data/default.effect

@@ -51,7 +51,7 @@ float4 PSDrawAlphaDivideR10L(VertInOut vert_in) : TARGET
 	rgba.rgb *= (rgba.a > 0.) ? (multiplier / rgba.a) : 0.;
 	rgba.rgb = rec709_to_rec2020(rgba.rgb);
 	rgba.rgb = linear_to_st2084(rgba.rgb);
-	uint3 rgb1023 = uint3(mad(rgba.rgb, 1023., .5));
+	uint3 rgb1023 = uint3(mad(rgba.rgb, 876., 64.5));
 	uint b = (rgb1023.b & 0x3Fu) << 2;
 	uint g = ((rgb1023.b & 0x3C0u) >> 6) | ((rgb1023.g & 0xFu) << 4);
 	uint r = ((rgb1023.g & 0x3F0u) >> 4) | ((rgb1023.r & 0x3u) << 6);