winrt: Enable webp for winrt arm configurations

The fix from upstream has landed in Qt so that webp can now be enabled for
that configuration as well.

Task-number: QTBUG-71251
Change-Id: I772decad30c91c6e028af05bdba0601ebd1574df
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

src/imageformats/configure.json

@@ -155,7 +155,7 @@
         "webp": {
             "label": "WEBP",
             "disable": "input.webp == 'no'",
-            "condition": "features.imageformatplugin && !(config.winrt && arch.arm)",
+            "condition": "features.imageformatplugin",
             "output": [
                 "privateFeature"
             ]