Bluetooth: Introduce hci_dev_do_reset helper function

Split the hci_dev_reset ioctl handling into using hci_dev_do_reset
helper function. Similar to what has been done with hci_dev_do_open
and hci_dev_do_close.

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