src/meta-openembedded:wireshark: fix Qt5/6 configuration

Wireshark is built with Qt6 by default when Qt is enabled.
Forcibly disable Qt6 in our Qt5 PACKAGECONFIG

Github issue: openembedded/meta-openembedded#844

Reported-by: Ludovic Jozeau <ludovic.jozeausmile.fr>
Reviewed-by: Yoann Congal <yoann.congalsmile.fr>
Signed-off-by: Ghislain Mangé <ghislain.mangesmile.fr>
Signed-off-by: Khem Raj <raj.khemgmail.com>