Bluetooth: btusb: Fix the autosuspend enable and disable

I tried to disable the autosuspend on btusb through the module
parameter enable_autosuspend, this parameter is set to N, but the usb
bluetooth device is still runtime suspended.
$ cat /sys/module/btusb/parameters/enable_autosuspend
N
$ cat /sys/bus/usb/devices/3-10/power/runtime_status
suspended
$ cat /sys/bus/usb/devices/3-10/power/runtime_suspended_time
65187

We already set ".supports_autosuspend = 1" in the usb_driver, this
device will be set autosuspend enabled by usb core, we don't need
to call usb_enable_autosuspend() in the btusb_probe(). Instead if
users set the parameter enable_autosuspend to N, we need to call
usb_disable_autosuspend() in the btusb_probe(). After this change
and set the parameter to N, we could see the device is not runtime
suspended anymore.
$ cat /sys/module/btusb/parameters/enable_autosuspend
N
$ cat /sys/bus/usb/devices/3-10/power/runtime_status
active
$ cat /sys/bus/usb/devices/3-10/power/runtime_suspended_time
0

And if we disable the autosuspend in the btusb_probe(), we need to
enable the autosuspend in the disconnect(), this could guarantee
that the device could be runtime suspended after we rmmod the btusb.

Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>