cnss: Add API to recover from PCI link down

Sometimes PCI framework and PCI bus driver fail to detect PCI link down
failure. Expose the API to WLAN host driver so that it can recover when
detects the failure by itself. Also expose an MSM PCIe API to WLAN host
driver which will used for MSM platform.

Change-Id: Ia49ef0728a3759190c0283a90ddcce4b465dd993
CRs-fixed: 707986
Signed-off-by: Yue Ma <yuem@codeaurora.org>