qt5-creator: Skip it when meta-python2 is not in layermix
qt5-creator: Skip it when meta-python2 is not in layermix

it depends on qtwebengine which inturn depends on chromium which inturn
depends on python2 during build. So lets disable it when meta-python2 is
not used until such time when chromium does not need python2

Signed-off-by: Khem Raj <729d64b6f67515e258459a5f6d20ec88b2caf8df@gmail.com>

schnitzeltony/meta-qt5,meta-qt5/meta-qt5,schnitzeltony/meta-qt5,meta-qt5/meta-qt5