kvmconfig: add more virtio drivers

"make defconfig kvmconfig" is supposed to end up with usable kernel for
KVM guest. In practice, it won't work for e.g. Hetzner VPS (KVM-based)
unless you add these options.
Signed-off-by: Andrey Utkin <andrey_utkin@fastmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/configs/kvm_guest.config

@@ -26,3 +26,6 @@ CONFIG_VIRTIO_NET=y
 CONFIG_9P_FS=y
 CONFIG_NET_9P=y
 CONFIG_NET_9P_VIRTIO=y
+CONFIG_SCSI_LOWLEVEL=y
+CONFIG_SCSI_VIRTIO=y
+CONFIG_VIRTIO_INPUT=y