Revert "Bluetooth: btusb: Configure altsetting for HCI_USER_CHANNEL"

This reverts commit 75ddcd5a.

This patch doesn't work quite well - It's observed that with this patch
HFP is flaky on most of the existing USB Bluetooth controllers: Intel
chips sometimes send out no packet for Transparent codec; MTK chips may
generate SCO data with a wrong handle for CVSD codec; RTK could split
the data with a wrong packet size for Transparent codec; ... etc.

Cc: chromeos-bluetooth-upstreaming@chromium.org
Signed-off-by: Hsin-chen Chuang <chharry@chromium.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>