cnss2: Set CNSS PM ops to PM domain

Directly register CNSS PM ops to PM domain so that runtime PM
core will avoid calling PCIe framework runtime PM callbacks. This
is able to help CNSS driver sync runtime PM suspend/resume with
any other PCIe bus suspend/resume requests.

Change-Id: Ib71f0bf8eb8f28d1a4334d59505a24470a19a816
Signed-off-by: Yue Ma <yuem@codeaurora.org>