Qt: fix F* keys in Preferences - #3827
Qt: fix F* keys in Preferences - #3827

KEY_F* are not consequential, while Qt::Key_F* are
Close #3827

krichter722/vlc,vlc-mirror/vlc-2.1,xkfz007/vlc,vlc-mirror/vlc,shyamalschandra/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,krichter722/vlc,jomanmuk/vlc-2.1,krichter722/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,krichter722/vlc,krichter722/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc,shyamalschandra/vlc,vlc-mirror/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc,krichter722/vlc,shyamalschandra/vlc,xkfz007/vlc,xkfz007/vlc,vlc-mirror/vlc-2.1,shyamalschandra/vlc,vlc-mirror/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,krichter722/vlc,xkfz007/vlc,vlc-mirror/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,xkfz007/vlc,jomanmuk/vlc-2.2,shyamalschandra/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,xkfz007/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,vlc-mirror/vlc