hikey960: Fix rtc0 hwtosys selinux denial

Noticed the audit denial on rtc hwtosys file:
01-01 03:50:51.146  2877  2877 W system_server: type=1400 audit(0.0:13): avc: denied { read } for name="hctosys" dev="sysfs" ino=14546 scontext=u:r:system_server:s0 tcontext=u:object_r:sysfs:s0 tclass=file permissive=0

So added this sepolicy change to address it.

Change-Id: Ie1302cf15eaee63f395c34a16352e60152eb0bf0
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/sepolicy/genfs_contexts b/sepolicy/genfs_contexts
index fbea22a..ef5b785 100644
--- a/sepolicy/genfs_contexts
+++ b/sepolicy/genfs_contexts
@@ -1,2 +1,3 @@
 # sysfs
 genfscon sysfs /devices/virtual/nanohub/nanohub       u:object_r:sysfs_nanoapp_cmd:s0
+genfscon sysfs /devices/platform/soc/fff04000.rtc/rtc	u:object_r:sysfs_rtc:s0