HID: i2c-hid: refactor reset command

"Reset" is the only command that needs to wait for interrupt from
the device before continuing, so let's factor our waiting logic from
__i2c_hid_command() to make it simpler.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Tested-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>