vsock/vmci: make vmci_vsock_cb_host_called static

When using make C=2 drivers/misc/vmw_vmci/vmci_driver.o
to compile, below warning can be seen:
drivers/misc/vmw_vmci/vmci_driver.c:33:6: warning:
symbol 'vmci_vsock_cb_host_called' was not declared. Should it be static?

This patch make symbol vmci_vsock_cb_host_called static.

Fixes: b1bba80 ("vsock/vmci: register vmci_transport only when VMCI guest/host are active")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Mao Wenan <maowenan@huawei.com>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/misc/vmw_vmci/vmci_driver.c

@@ -30,7 +30,7 @@ static bool vmci_host_personality_initialized;
 
 static DEFINE_MUTEX(vmci_vsock_mutex); /* protects vmci_vsock_transport_cb */
 static vmci_vsock_cb vmci_vsock_transport_cb;
-bool vmci_vsock_cb_host_called;
+static bool vmci_vsock_cb_host_called;
 
 /*
  * vmci_get_context_id() - Gets the current context ID.