ASoC: Intel: bxt_da7219_max98357a: shrink platform_id below 20 characters

ASoC: Intel: bxt_da7219_max98357a: shrink platform_id below 20 characters

Sparse throwns the following warnings:

sound/soc/intel/boards/bxt_da7219_max98357a.c:843:19: error: too long
initializer-string for array of char(no space for nul char)

sound/soc/intel/boards/bxt_da7219_max98357a.c:844:19: error: too long
initializer-string for array of char(no space for nul char)

sound/soc/intel/boards/bxt_da7219_max98357a.c:845:19: error: too long
initializer-string for array of char(no space for nul char)

Fix by using the 'mx' acronyn for Maxim

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Paul Olaru <paul.olaru@oss.nxp.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Link: https://lore.kernel.org/r/20210511213707.32958-5-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>