The core specification defines valid values for the
HCI_Reject_Synchronous_Connection_Request command to be 0x0D-0x0F. So
far the code has been using HCI_ERROR_REMOTE_USER_TERM (0x13) which is
not a valid value and is therefore being rejected by some controllers:

 > HCI Event: Connect Request (0x04) plen 10
	bdaddr 40:6F:2A:6A:E5:E0 class 0x000000 type eSCO
 < HCI Command: Reject Synchronous Connection (0x01|0x002a) plen 7
	bdaddr 40:6F:2A:6A:E5:E0 reason 0x13
	Reason: Remote User Terminated Connection
 > HCI Event: Command Status (0x0f) plen 4
	Reject Synchronous Connection (0x01|0x002a) status 0x12 ncmd 1
	Error: Invalid HCI Command Parameters

This patch introduces a new define for a value from the valid range
(0x0d == Connection Rejected Due To Limited Resources) and uses it
instead for rejecting incoming connections.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>