init: fix subcontext SELinux strings

'object_r' is supposed to be simply 'r'.

Test: boot sailfish with SELinux fully enabled and subcontexts enabled
Change-Id: I7eb8b2dd18e66f23c09863e8961da339f72d25c5
diff --git a/init/subcontext.cpp b/init/subcontext.cpp
index 1306c7d..85da237 100644
--- a/init/subcontext.cpp
+++ b/init/subcontext.cpp
@@ -40,8 +40,8 @@
 namespace android {
 namespace init {
 
-const std::string kInitContext = "u:object_r:init:s0";
-const std::string kVendorContext = "u:object_r:vendor_init:s0";
+const std::string kInitContext = "u:r:init:s0";
+const std::string kVendorContext = "u:r:vendor_init:s0";
 
 namespace {