Call qtUpdateApi on module as expected

The qtUpdateDpi function is a module function, not a scope function
(regardless of it being window-scope self or QtLoader-scope self).
Therefore it should be executed with module as this.

Fixes: QTBUG-108112
Pick-to: 6.4
Change-Id: Ib4604a43dbdd0caa114d3d892ea97b5ee4c9a9a8
Reviewed-by: Aleksandr Reviakin <aleksandr.reviakin@qt.io>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

src/plugins/platforms/wasm/qtloader.js

@@ -581,7 +581,7 @@ function _QtLoader(config)
     function setFontDpi(dpi) {
         self.qtFontDpi = dpi;
         if (publicAPI.status == "Running")
-            self.qtUpdateDpi();
+            self.module.qtUpdateDpi();
     }
 
     function fontDpi() {