Revert "Add keychain user"

This reverts commit 6541ef1562ccf93e498d653598330a7fc80ad2b2.

Bug:4970237
Change-Id: I23a90eb89c1d19893d2ba7065fc624c0521cb06e
diff --git a/include/private/android_filesystem_config.h b/include/private/android_filesystem_config.h
index 6e42ae9..fc71a1e 100644
--- a/include/private/android_filesystem_config.h
+++ b/include/private/android_filesystem_config.h
@@ -53,7 +53,7 @@
 #define AID_KEYSTORE      1017  /* keystore subsystem */
 #define AID_USB           1018  /* USB devices */
 #define AID_DRM           1019  /* DRM server */
-#define AID_KEYCHAIN      1020  /* keychain service */
+#define AID_AVAILABLE     1020  /* available for use */
 #define AID_GPS           1021  /* GPS daemon */
 #define AID_UNUSED1       1022  /* deprecated, DO NOT USE */
 #define AID_MEDIA_RW      1023  /* internal media storage write access */
@@ -103,7 +103,7 @@
     { "install",   AID_INSTALL, },
     { "media",     AID_MEDIA, },
     { "drm",       AID_DRM, },
-    { "keychain",  AID_KEYCHAIN, },
+    { "available", AID_AVAILABLE, },
     { "nfc",       AID_NFC, },
     { "shell",     AID_SHELL, },
     { "cache",     AID_CACHE, },