ASoC: cs42l56: Fix reset GPIO name in example DT binding

The binding states the reset GPIO property shall be named
"cirrus,gpio-nreset" and this is what the driver looks for,
but the example uses "gpio-reset". Fix this here.

Fixes: 3bb40619 ("ASoC: cs42l56: bindings: sound: Add bindings for CS42L56 CODEC")

Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>