VMCI: remove set but not used variable 'cid'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/misc/vmw_vmci/vmci_host.c: In function 'vmci_host_do_alloc_queuepair':
drivers/misc/vmw_vmci/vmci_host.c:450:6: warning:
 variable 'cid' set but not used [-Wunused-but-set-variable]
  u32 cid;
      ^

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>