interconnect: drop racy registration API

Now that all interconnect drivers have been converted to the new
provider registration API, the old racy interface can be removed.

Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20230306075651.2449-22-johan+linaro@kernel.org


Signed-off-by: Georgi Djakov <djakov@kernel.org>