usb: usb251xb: Use GPIO descriptor consumer interface

The driver used to be developed with legacy GPIO API support. It's
better to use descriptor-based interface for several reasons. First
of all the legacy API doesn't support the ACTIVE_LOW/HIGH flag of dts
nodes, which is essential since different hardware may have different
GPIOs connectivity including the logical value inversion. Secondly,
by requesting the reset GPIO descriptor the driver prevent the other
applications from changing its value. And last but not least the
legacy GPIO interface should be avoided in the new code due to it
obsolescence.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>