cnss: comment cnss_msm_pcie_pm_control at GreenHills platform

It doesn't support virtualized clock currently,
so we cannot disable/enable clock while do PCIE link
suspend/resume from Linux side at Greenhills platform,
so comment the API cnss_msm_pcie_pm_control to prevent
doing PCIE link suspend/resume.

Change-Id: Ie10d781042ff3e85b3206fd300e9ec3f71897479
Signed-off-by: Chaoli Zhou <zchaoli@codeaurora.org>