[ARM] dns323-setup.c: fix WARN() when booting

Since commit b2a731aa5cbca7e0252da75e16de7ae5feb1313a, dns323_init() is
setting the power led gpio direction with gpio_direction_output() but
doesn't request the gpio before (which is not permitted by the gpio
layer afaik). This behaviour is triggering a WARN() at boot time.

Tested-by: Christian Samsel <csamsel@gmxpro.de>
Cc: Martin Michlmayr <tbm@cyrius.com>
Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Nicolas Pitre <nico@marvell.com>
    [ Part 2: "Attached Text" ]