Bluetooth: remove redundant variables 'adv_set' and 'cp'

Variables 'adv_set' and 'cp'  are being assigned but are never used hence
they are redundant and can be removed.

Cleans up clang warnings:
net/bluetooth/hci_event.c:1135:29: warning: variable 'adv_set' set but not used [-Wunused-but-set-variable]
net/bluetooth/mgmt.c:3359:39: warning: variable 'cp' set but not used [-Wunused-but-set-variable]

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>