kunit: test.h: fix a bad kernel-doc markup

As warned by:

	./include/kunit/test.h:504: WARNING: Block quote ends without a blank line; unexpected unindent.

The right way to describe a function is:

	name - description

Instead, kunit_remove_resource was using:

	name: description

Causing it to be improperly parsed.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>