Bluetooth: hci_get_cmd_complete() can be static

There are new sparse warnings show up in

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next

 master
head:   a0b644b0385fa58ca578f6dce4473e8a8e6f6c38
commit: 75e84b7c Bluetooth: Add __hci_cmd_sync() helper function
date:   13 days ago

>> net/bluetooth/hci_core.c:82:16: sparse: symbol 'hci_get_cmd_complete' was not declared. Should it be static?

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>