ASoC: rt5670: Rename dev_gpio to gpio1_is_irq

Rename the not really descriptive dev_gpio quirk / setting to
gpio1_is_irq, which describes what it actually does.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200703100823.258033-3-hdegoede@redhat.com
Signed-off-by: Mark Brown <broonie@kernel.org>