vo_opengl: hwdec_d3d11egl: remove ES2 swizzle special-case

This was somehow done under the assumption that ANGLE would somehow
always use RG in ES2 mode. But there's no basis for this. Even if ANGLE
supports NV12 textures with drivers that do not allow for texture_rg,
this cas eis too obscure to worry about. So do the robust and correct
thing instead, and disable this code if texture_rg is not available.

video/out/opengl/hwdec_d3d11egl.c

@@ -114,7 +114,8 @@ static int create(struct gl_hwdec *hw)
         !strstr(exts, "EGL_ANGLE_stream_producer_d3d_texture_nv12") ||
         !(strstr(hw->gl->extensions, "GL_OES_EGL_image_external_essl3") ||
           hw->gl->es == 200) ||
-        !strstr(exts, "EGL_EXT_device_query"))
+        !strstr(exts, "EGL_EXT_device_query") ||
+        !(hw->gl->mpgl_caps & MPGL_CAP_TEX_RG))
         return -1;
 
     HRESULT hr;
@@ -309,7 +310,6 @@ static int map_frame(struct gl_hwdec *hw, struct mp_image *hw_image,
                 .gl_target = GL_TEXTURE_EXTERNAL_OES,
                 .tex_w = texdesc.Width / 2,
                 .tex_h = texdesc.Height / 2,
-                .swizzle = "rgba", // even in ES2 mode (no LUMINANCE_ALPHA)
             },
         },
     };