MAINTAINERS: Add interconnect kunit test entry

Add an entry for the interconnect Kunit tests. As the original author
of this test suite, I would like to be notified of future related
patches so I can help review them.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Link: https://msgid.link/20260320190623.1846992-1-visitorckw@gmail.com
Signed-off-by: Georgi Djakov <djakov@kernel.org>