MAINTAINERS: Add KVM x86/xen maintainer list

Adding Paul as co-maintainer of Xen support to help ensure that things
don't fall through the cracks when I spend three months at a time
travelling...
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -11324,6 +11324,16 @@ F:	arch/x86/kvm/svm/hyperv.*
 F:	arch/x86/kvm/svm/svm_onhyperv.*
 F:	arch/x86/kvm/vmx/evmcs.*
 
+KVM X86 Xen (KVM/Xen)
+M:	David Woodhouse <dwmw2@infradead.org>
+M:	Paul Durrant <paul@xen.org>
+M:	Sean Christopherson <seanjc@google.com>
+M:	Paolo Bonzini <pbonzini@redhat.com>
+L:	kvm@vger.kernel.org
+S:	Supported
+T:	git git://git.kernel.org/pub/scm/virt/kvm/kvm.git
+F:	arch/x86/kvm/xen.*
+
 KERNFS
 M:	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 M:	Tejun Heo <tj@kernel.org>