HID: steam: fix boot loop with bluetooth firmware

There is a new firmware for the Steam Controller with support for BLE
connections. When using such a device with a wired connection, it
reboots itself every 10 seconds unless an application has opened it.

Doing hid_hw_open() unconditionally on probe fixes the issue, and the
code becomes simpler.

Signed-off-by: Rodrigo Rivas Costa <rodrigorivascosta@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>