ALSA: Kconfig: add config item SND_PROC_FS for expert

For some embedded devices, we need reduce code size and data
footprint as much as possible, e.g. disabling procfs, hw/sw
params refinement, mmap, dpcm, dapm, compressed API...

Here add SND_PROC_FS item for expert, we can unselect it to
disable sound proc FS and reduce memory footprint.

Signed-off-by: Jie Yang <yang.jie@intel.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>