ASoC: intel: skylake: Drop superfluous mmap callback

skl_platform_soc_mmap() just calls the standard mmap helper, hence
it's superfluous.  Let's drop it.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20210728141930.17740-1-tiwai@suse.de


Signed-off-by: Mark Brown <broonie@kernel.org>