Bluetooth: hci_core: Fix not handling hdev->le_num_of_adv_sets=1

If hdev->le_num_of_adv_sets is set to 1 it means that only handle 0x00
can be used, but since the MGMT interface instances start from 1
(instance 0 means all instances in case of MGMT_OP_REMOVE_ADVERTISING)
the code needs to map the instance to handle otherwise users will not be
able to advertise as instance 1 would attempt to use handle 0x01.

Fixes: 1d0fac2c

 ("Bluetooth: Use controller sets when available")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>