Expand rtc_device label to match all rtc class drivers.

/dev/rtc0 is not the only possible rtc device node, make sure all are given the
rtc_device label.

(cherry-pick of 1b4b3b91)

Change-Id: Iea6e1271fb054ea7f44860724e04143875867d78

file_contexts

@@ -77,7 +77,7 @@
 /dev/random		u:object_r:random_device:s0
 /dev/rpmsg-omx[0-9]	u:object_r:rpmsg_device:s0
 /dev/rproc_user	u:object_r:rpmsg_device:s0
-/dev/rtc0           u:object_r:rtc_device:s0
+/dev/rtc[0-9]      u:object_r:rtc_device:s0
 /dev/snd(/.*)?		u:object_r:audio_device:s0
 /dev/socket(/.*)?	u:object_r:socket_device:s0
 /dev/socket/adbd	u:object_r:adbd_socket:s0