Bluetooth: hci_event: Fix build warning with C=1

This fixes the following warning when build with make C=1:

net/bluetooth/hci_event.c:337:15: warning: restricted __le16 degrades to integer

Fixes: a9366120 ("Bluetooth: Process result of HCI Delete Stored Link Key command")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>