update_verifier: correct group in rc file

update_verifier should be in the cache group, not 'class'.

Also use PLOG instead of LOG if care_map.txt cannot be opened.

Bug: 36818743
Test: boot sailfish
Test: fake OTA on sailfish and verify update_verifier reads care_package
Change-Id: I0ec844cac5ef5c63b18ebee90160854fd84ee829
diff --git a/update_verifier/update_verifier.rc b/update_verifier/update_verifier.rc
index fc8a64d..75cfeb2 100644
--- a/update_verifier/update_verifier.rc
+++ b/update_verifier/update_verifier.rc
@@ -1,11 +1,11 @@
 service update_verifier_nonencrypted /system/bin/update_verifier nonencrypted
     user root
-    class cache
+    group cache
     priority -20
     ioprio rt 1
 
 service update_verifier /system/bin/update_verifier ${vold.decrypt}
     user root
-    class cache
+    group cache
     priority -20
     ioprio rt 1
\ No newline at end of file