iOS: Remove dead code for linking to platform plugin

The code only existed to avoid the auto-generated
Q_IMPORT_PLUGIN(QIOSIntegrationPlugin), but nowadays
with bitcode enabled the code is not used, plus we end
up with this auto-generated file for other plugins anyways.

Change-Id: I91c8c88f4e825caab7d7d5250edaba8c57cb7374
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

mkspecs/features/uikit/qt.prf

@@ -1,25 +1,6 @@
 
 qt_depends = $$resolve_depends(QT, "QT.")
 !watchos:equals(TEMPLATE, app):contains(qt_depends, gui(-private)?) {
-    LIBS *= -L$$[QT_INSTALL_PLUGINS/get]/platforms
-
-    lib_name = qios
-    lib_path_and_base = $$[QT_INSTALL_PLUGINS/get]/platforms/lib$${lib_name}$$qtPlatformTargetSuffix()
-    LIBS += -l$${lib_name}$$qtPlatformTargetSuffix() $$fromfile($${lib_path_and_base}.prl, QMAKE_PRL_LIBS)
-
-    !bitcode {
-        # By marking qt_registerPlatformPlugin as undefined, we ensure that
-        # the plugin.o translation unit is considered for inclusion in
-        # the final binary, which in turn ensures that the plugin's
-        # static initializer is included and run.
-        QMAKE_LFLAGS += -u _qt_registerPlatformPlugin
-
-        # We do link and dependency resolution for the platform plugin
-        # manually, since we know we always need the plugin, so we don't
-        # need to generate an import for it.
-        QTPLUGIN.platforms = -
-    }
-
     !no_main_wrapper {
         # The LC_MAIN load command available in iOS 6.0 and above allows dyld to
         # directly call the entrypoint instead of going through _start in crt.o.