Bluetooth: Fix reason code used for rejecting SCO connections

A comment in the code states that SCO connection should be rejected
with the proper error value between 0xd-0xf. The code uses
HCI_ERROR_REMOTE_LOW_RESOURCES which is 0x14.

This led to following error:
< HCI Command: Reject Synchronous Co.. (0x01|0x002a) plen 7
        Address: 34:51:C9:EF:02:CA (Apple, Inc.)
        Reason: Remote Device Terminated due to Low Resources (0x14)
> HCI Event: Command Status (0x0f) plen 4
      Reject Synchronous Connection Request (0x01|0x002a) ncmd 1
        Status: Invalid HCI Command Parameters (0x12)

Instead make use of HCI_ERROR_REJ_LIMITED_RESOURCES which is 0xd.

Signed-off-by: Frédéric Dalleau <frederic.dalleau@collabora.co.uk>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>