MAINTAINERS: keys: Update path to trusted.h

Update MAINTAINERS record to reflect that trusted.h
was moved to a different directory in commit 22447981
("KEYS: Move trusted.h to include/keys [ver #2]").

Cc: Denis Kenzior <denkenz@gmail.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: linux-integrity@vger.kernel.org
Signed-off-by: Denis Efremov <efremov@linux.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>