wpa_gui-qt4: remove qPixmapFromMimeSource from ui files

wpa_gui-qt4: remove qPixmapFromMimeSource from ui files

When integrating the new art, this UI entry:

<pixmapfunction>qPixmapFromMimeSource</pixmapfunction>

Caused the following error:

.obj/wpagui.o: In function `Ui_WpaGui::setupUi(QMainWindow*)':
wpagui.cpp:(.text._ZN9Ui_WpaGui7setupUiEP11QMainWindow[Ui_WpaGui::setupUi(QMainWindow*)]+0xd3): undefined reference to `qPixmapFromMimeSource(QString const&)'
collect2: ld returned 1 exit status

Removing qPixmapFromMimeSource seems to have no unwanted side effects, and
allows successful build again. Research leads me to believe it depends on
Qt3Support, which we do not want.

Signed-off-by: Kel Modderman <kel@otaku42.de>