KVM: Move common KVM Kconfig items to new file virt/kvm/Kconfig

Reduce Kconfig code duplication.

Signed-off-by: Avi Kivity <avi@redhat.com>

arch/s390/kvm/Kconfig

@@ -1,11 +1,7 @@
 #
 # KVM configuration
 #
-config HAVE_KVM
-       bool
-
-config HAVE_KVM_IRQCHIP
-       bool
+source "virt/kvm/Kconfig"
 
 menuconfig VIRTUALIZATION
 	bool "Virtualization"