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.

Force bilinear if dumb mode is enabled.

video/out/gpu/video.c

@@ -3863,8 +3863,18 @@ static void check_gl_features(struct gl_video *p)
                        "Most extended features will be disabled.\n");
         }
         p->dumb_mode = true;
+        static const struct scaler_config dumb_scaler_config = {
+            {"bilinear", .params = {NAN, NAN}},
+            {.params = {NAN, NAN}},
+        };
         // Most things don't work, so whitelist all options that still work.
         p->opts = (struct gl_video_opts){
+            .scaler = {
+                [SCALER_SCALE] = dumb_scaler_config,
+                [SCALER_DSCALE] = dumb_scaler_config,
+                [SCALER_CSCALE] = dumb_scaler_config,
+                [SCALER_TSCALE] = dumb_scaler_config,
+            },
             .gamma = p->opts.gamma,
             .gamma_auto = p->opts.gamma_auto,
             .pbo = p->opts.pbo,
@@ -3888,8 +3898,6 @@ 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;