ASoC: Intel: bytcr_rt5640: Make rt5640_jack_gpio/rt5640_jack2_gpio static

Marking the two jack gpio as static fixes the following Sparse errors:
sound/soc/intel/boards/bytcr_rt5640.c:468:26: error: symbol 'rt5640_jack_gpio' was not declared. Should it be static?
sound/soc/intel/boards/bytcr_rt5640.c:475:26: error: symbol 'rt5640_jack2_gpio' was not declared. Should it be static?

Fixes: 9ba00856 ("ASoC: Intel: bytcr_rt5640: Add support for HP Elite Pad 1000G2 jack-detect")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20210825122519.3364-1-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/boards/bytcr_rt5640.c

@@ -465,14 +465,14 @@ static struct snd_soc_jack_pin rt5640_pins2[] = {
 	},
 };
 
-struct snd_soc_jack_gpio rt5640_jack_gpio = {
+static struct snd_soc_jack_gpio rt5640_jack_gpio = {
 	.name = "hp-detect",
 	.report = SND_JACK_HEADSET,
 	.invert = true,
 	.debounce_time = 200,
 };
 
-struct snd_soc_jack_gpio rt5640_jack2_gpio = {
+static struct snd_soc_jack_gpio rt5640_jack2_gpio = {
 	.name = "hp2-detect",
 	.report = SND_JACK_HEADSET,
 	.invert = true,