DO NOT MERGE Restore calling identity before checking permission

Using the system service identity to check the CHANGE_CONFIGURATION
permission isn't likely to catch a security violation. Changing
back to the original caller and then checking permissions is
preferred.

Cherry picked from lmp. Fixes bug 15989465.

Change-Id: Iff08d04422bcc052a487194154f1fd0d727d38f4
1 file changed