ASoC: Intel: bytcr_rt5640: Make rt5640_jack_gpio/rt5640_jack2_gpio static

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: 4a57458959229 ("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.com
Signed-off-by: Mark Brown <broonie@kernel.org>