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 <[e-mail]>
Reviewed-by: Mark Brown <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

sound/core/Kconfig

···
 	  Say Y here to support the obsolete ALSA PCM API (ver.0.9.0 rc3
 	  or older).
 
+config SND_PROC_FS
+        bool "Sound Proc FS Support" if EXPERT
+        depends on PROC_FS
+        default y
+        help
+          Say 'N' to disable Sound proc FS, which may reduce code size about
+          9KB on x86_64 platform.
+          If unsure say Y.
+
 config SND_VERBOSE_PROCFS
 	bool "Verbose procfs contents"
-	depends on PROC_FS
+	depends on SND_PROC_FS
 	default y
 	help
 	  Say Y here to include code for verbose procfs contents (provides