kunit: Clarify kunit_skip() argument name

kunit_skip() and kunit_mark_skipped() can only be passed a pointer
to a struct kunit, not struct kunit_suite (only kunit_log() actually
supports both). Rename their first argument accordingly.

Link: https://lore.kernel.org/r/20250217140008.1941287-1-kevin.brodsky@arm.com


Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>