vo_gpu: don't override scaler options with default ones

There was assumption in the code that default settings are compatible
with dumb mode and are only one that should be used in this case.

Use proper settings from user after checking that they are dumb.

video/out/gpu/video.c

@@ -3865,6 +3865,12 @@ static void check_gl_features(struct gl_video *p)
         p->dumb_mode = true;
         // Most things don't work, so whitelist all options that still work.
         p->opts = (struct gl_video_opts){
+            .scaler = {
+                [SCALER_SCALE] = p->opts.scaler[SCALER_SCALE],
+                [SCALER_DSCALE] = p->opts.scaler[SCALER_DSCALE],
+                [SCALER_CSCALE] = p->opts.scaler[SCALER_CSCALE],
+                [SCALER_TSCALE] = p->opts.scaler[SCALER_TSCALE],
+            },
             .gamma = p->opts.gamma,
             .gamma_auto = p->opts.gamma_auto,
             .pbo = p->opts.pbo,
@@ -3888,8 +3894,6 @@ static void check_gl_features(struct gl_video *p)
             .target_prim = p->opts.target_prim,
             .target_peak = p->opts.target_peak,
         };
-        for (int n = 0; n < SCALER_COUNT; n++)
-            p->opts.scaler[n] = gl_video_opts_def.scaler[n];
         if (!have_fbo)
             p->use_lut_3d = false;
         return;