Bluetooth: mgmt: Implement Cancel Pair Device command

This patch implements the Cancel Pair Device command for mgmt. It's used
by user space to cancel an ongoing pairing attempt which was triggered
by the Pair Device command.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/mgmt.h

@@ -39,6 +39,7 @@
 #define MGMT_STATUS_INVALID_PARAMS	0x0d
 #define MGMT_STATUS_DISCONNECTED	0x0e
 #define MGMT_STATUS_NOT_POWERED		0x0f
+#define MGMT_STATUS_CANCELLED		0x10
 
 struct mgmt_hdr {
 	__le16 opcode;