KVM: x86: introduce kvm_check_has_quirk

The logic of the disabled_quirks field usually results in a double
negation.  Wrap it in a simple function that checks the bit and
negates it.

Based on a patch from Xiao Guangrong.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --cc arch/x86/kvm/lapic.c
Simple merge

diff --cc arch/x86/kvm/svm.c
Simple merge

diff --cc arch/x86/kvm/x86.h
Simple merge