procd: emit events for sound subsystem

Useful e.g. for plugable USB-soundcards.
With this change an event/hotplug-call looks like:

ACTION: add DEVNAME: snd/timer DEVPATH: /devices/virtual/sound/timer SUBSYSTEM: sound
ACTION: add DEVNAME:  DEVPATH: /devices/platform/ehci-platform/usb1/1-1/1-1:1.0/sound/card0 SUBSYSTEM: sound
ACTION: add DEVNAME: snd/controlC0 DEVPATH: /devices/platform/ehci-platform/usb1/1-1/1-1:1.0/sound/card0/controlC0 SUBSYSTEM: sound
ACTION: add DEVNAME: snd/pcmC0D0p DEVPATH: /devices/platform/ehci-platform/usb1/1-1/1-1:1.0/sound/card0/pcmC0D0p SUBSYSTEM: sound
ACTION: add DEVNAME: snd/pcmC0D0c DEVPATH: /devices/platform/ehci-platform/usb1/1-1/1-1:1.0/sound/card0/pcmC0D0c SUBSYSTEM: sound
ACTION: add DEVNAME: dsp DEVPATH: /devices/platform/ehci-platform/usb1/1-1/1-1:1.0/sound/card0/dsp SUBSYSTEM: sound
ACTION: add DEVNAME: audio DEVPATH: /devices/platform/ehci-platform/usb1/1-1/1-1:1.0/sound/card0/audio SUBSYSTEM: sound
ACTION: add DEVNAME: mixer DEVPATH: /devices/platform/ehci-platform/usb1/1-1/1-1:1.0/sound/card0/mixer SUBSYSTEM: sound

This fixes #21466.

Signed-off-by: Bastian Bittorf <bittorf@bluebottle.com>

SVN-Revision: 48366

package/system/procd/files/hotplug.json

@@ -70,7 +70,7 @@
 	],
 	[ "if",
 		[ "eq", "SUBSYSTEM",
-			[ "net", "input", "usb", "usbmisc", "ieee1394", "block", "atm", "zaptel", "tty", "button" ]
+			[ "net", "input", "usb", "usbmisc", "ieee1394", "block", "atm", "zaptel", "tty", "button", "sound" ]
 		],
 		[ "exec", "/sbin/hotplug-call", "%SUBSYSTEM%" ]
 	],