ASoC: intel: Remove unused variable hsw

The recent fix left a variable declaration without usage.
  sound/soc/intel/haswell/sst-haswell-pcm.c:1349:18: warning: unused variable ‘hsw’ [-Wunused-variable]

Fixes: edd8ed49 ('ASoC: Intel: handle haswell pcm suspend including runtime modules freeing')
Signed-off-by: Takashi Iwai <tiwai@suse.de>