cameraserver: add input group

It is required by some input device node access.

Bug: 28914535
Change-Id: I863bfe6014b316c6e0113327f631555fcb0d28d3
diff --git a/camera/cameraserver/cameraserver.rc b/camera/cameraserver/cameraserver.rc
index 16d9da8..09f9789 100644
--- a/camera/cameraserver/cameraserver.rc
+++ b/camera/cameraserver/cameraserver.rc
@@ -1,6 +1,6 @@
 service cameraserver /system/bin/cameraserver
     class main
     user cameraserver
-    group audio camera drmrpc inet media mediadrm net_bt net_bt_admin net_bw_acct
+    group audio camera input drmrpc inet media mediadrm net_bt net_bt_admin net_bw_acct
     ioprio rt 4
     writepid /dev/cpuset/foreground/tasks