pci: controller: msm: Poll for L0s state when disallowing L1

If L0s link state is enabled, API to disallow L1 also needs
to poll for L0s while checking for L0. It is possible that
link goes to L0s from L0 by the time LTSSM state is checked
again.

Change-Id: Ib614860dad8c92a55f993cdb1c38bf8ebfca17a2
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>