By allowing the filter_glob parameter to be written to, it's possible to
tweak the testsuites that will be executed on new module loads. This
makes it easier to run specific tests without having to reload kunit and
provides a way to filter tests on real HW even if kunit is builtin.
Example for xe driver:

1) Run just 1 test
	# echo -n xe_bo > /sys/module/kunit/parameters/filter_glob
	# modprobe -r xe_live_test
	# modprobe xe_live_test
	# ls /sys/kernel/debug/kunit/
	xe_bo

2) Run all tests
	# echo \* > /sys/module/kunit/parameters/filter_glob
	# modprobe -r xe_live_test
	# modprobe xe_live_test
	# ls /sys/kernel/debug/kunit/
	xe_bo  xe_dma_buf  xe_migrate  xe_mocs

For completeness and to cover other use cases, also change filter and
filter_action to rw.

Link: https://lore.kernel.org/intel-xe/dzacvbdditbneiu3e3fmstjmttcbne44yspumpkd6sjn56jqpk@vxu7sksbqrp6/Reviewed-by: Rae Moar <rmoar@google.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>