scsi: ufs: add power management support for pci driver

ufshcd-pci driver is currently don't have runtime and system PM
callbacks implemented. This patch adds the support for the same which
would call the common ufshcd runtime/system PM callbacks.

Change-Id: I4aeaa41e681d0b6118eaa02054e6a44b5e7c303e
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>