MAINTAINERS: coresight: Add missing Coresight files

There are a few files missing from the list like test_arm_coresight.sh
and arm-coresight.txt so add the missing entries.

Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20231020154103.55936-1-james.clark@arm.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>