staging: serqt_usb2: don't use sleep_on

sleep_on and related functions are going away and should not be used
in this driver any more.

This removes the call to interruptible_sleep_on for a wait queue that
is never woken up, and replaces an interruptible_sleep_on_timeout
call with the equivalent wait_event_interruptible_timeout() to
avoid a small race.

Both call sites still look fishy and need more work.

Signed-off-by: Arnd Bergmann <arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: devel@driverdev.osuosl.org
Cc: Bill Pemberton <wfp5p@virginia.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>