meson: drop deprecated EGL platform build options
These two options were deprecated and announced to be removed in 20.3, so let's drop them now. Signed-off-by:Eric Engestrom <eric@engestrom.ch> Acked-by:
Emil Velikov <emil.velikov@collabora.com> Acked-by:
Matt Turner <mattst88@gmail.com> Reviewed-by:
Adam Jackson <ajax@redhat.com> Cc: 20.3 <mesa-stable> Part-of: <mesa/mesa!5844>