Add separate permission and group for access to MTP USB driver

Since the "usb" group and ACCESS_USB permission will be used by regular apps
to access USB devices in host mode, we need a separate permission for the
device side MTP driver.

Change-Id: Ibb546b8726d61e041fc7c273f71929624ad1575b
Signed-off-by: Mike Lockwood <lockwood@android.com>

include/private/android_filesystem_config.h

@@ -57,6 +57,7 @@
 #define AID_GPS           1021  /* GPS daemon */
 #define AID_NFC           1022  /* nfc subsystem */
 #define AID_MEDIA_RW      1023  /* internal media storage write access */
+#define AID_MTP           1024  /* MTP USB driver access */
 
 #define AID_SHELL         2000  /* adb and debug shell user */
 #define AID_CACHE         2001  /* cache access */
@@ -111,6 +112,7 @@ static const struct android_id_info android_ids[] = {
     { "vpn",       AID_VPN, },
     { "keystore",  AID_KEYSTORE, },
     { "usb",       AID_USB, },
+    { "mtp",       AID_MTP, },
     { "gps",       AID_GPS, },
     { "inet",      AID_INET, },
     { "net_raw",   AID_NET_RAW, },

rootdir/ueventd.rc

@@ -69,7 +69,7 @@
 /dev/qmi1                 0640   radio      radio
 /dev/qmi2                 0640   radio      radio
 /dev/bus/usb/*            0660   root       usb
-/dev/mtp_usb              0660   root       usb
+/dev/mtp_usb              0660   root       mtp
 
 # CDMA radio interface MUX
 /dev/ts0710mux*           0640   radio      radio