mako: add /dev/diag node.

In order to log vendor RIL logs, diag must have radio permissions.

Change-Id: I79a1bc7324ef0402790300dfef353629009cf47f
diff --git a/ueventd.mako.rc b/ueventd.mako.rc
index dd5da1f..a24e82f 100644
--- a/ueventd.mako.rc
+++ b/ueventd.mako.rc
@@ -29,6 +29,7 @@
 /dev/hsicctl1             0640   radio      radio
 /dev/hsicctl2             0640   radio      radio
 /dev/hsicctl3             0640   radio      radio
+/dev/diag                 0660   radio      radio
 /dev/video*               0660   system     camera
 /dev/media*               0660   system     camera
 /dev/v4l-subdev*          0660   system     camera