kunit: test.h: solve kernel-doc warnings

There are some warnings there:
	./include/kunit/test.h:90: warning: Function parameter or member 'name' not described in 'kunit_resource'
	./include/kunit/test.h:353: warning: Function parameter or member 'res' not described in 'kunit_add_resource'
	./include/kunit/test.h:367: warning: Function parameter or member 'res' not described in 'kunit_add_named_resource'
	./include/kunit/test.h:367: warning: Function parameter or member 'name' not described in 'kunit_add_named_resource'
	./include/kunit/test.h:367: warning: Function parameter or member 'data' not described in 'kunit_add_named_resource'
	./include/kunit/test.h:367: warning: Excess function parameter 'name_data' description in 'kunit_add_named_resource'

Address them, ensuring that all non-private arguments will
be properly described. With that regards, at struct kunit_resource,
the free argument is described as user-provided. So, this
doesn't seem to belong to the "private" part of the struct.

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