sepolicy: Allow system server and uncrypt access pipe

System server needs to be able to create a pipe in the cache partition
for uncrypting OTAs. Uncrypt needs to be able to read and write the
pipe.

Change-Id: Ie03ee7d637eaecff8fe38bf03dc733b3915cd336
diff --git a/sepolicy/uncrypt.te b/sepolicy/uncrypt.te
index 2e545a7..978f9e1 100644
--- a/sepolicy/uncrypt.te
+++ b/sepolicy/uncrypt.te
@@ -1,3 +1,4 @@
 r_dir_file(uncrypt, media_rw_data_file)
 allow uncrypt recovery_cache_file:dir create_dir_perms;
 allow uncrypt recovery_cache_file:file create_file_perms;
+allow uncrypt recovery_cache_file:fifo_file rw_file_perms;