kconfig qconf: fix -Wall compiler warnings

These compiler warnings occure when adding -Wall to HOSTCXXFLAGS in
/Makefile

scripts/kconfig/qconf.h: In constructor ‘ConfigInfoView::ConfigInfoView(QWidget*, const char*)’:
scripts/kconfig/qconf.h:274: warning: ‘ConfigInfoView::menu’ will be initialized after
scripts/kconfig/qconf.h:273: warning:   ‘symbol* ConfigInfoView::sym’
scripts/kconfig/qconf.cc:922: warning:   when initialized here

scripts/kconfig/qconf.cc: In member function ‘void ConfigMainWindow::setMenuLink(menu*)’:
scripts/kconfig/qconf.cc:1498: warning: enumeration value ‘menuMode’ not handled in switch
scripts/kconfig/qconf.cc:1498: warning: enumeration value ‘listMode’ not handled in switch

scripts/kconfig/qconf.cc: In member function ‘void ConfigMainWindow::saveSettings()’:
scripts/kconfig/qconf.cc:1664: warning: enumeration value ‘menuMode’ not handled in switch
scripts/kconfig/qconf.cc:1664: warning: enumeration value ‘listMode’ not handled in switch

Signed-off-by: Markus Heidelberg <markus.heidelberg@web.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>