cnss2: Keep a default copy of PCI config space

Since PCIe bus driver is going to deprecate msm_pcie_recover_config
API, PCIe device driver needs to keep a default copy of PCI config
space after PCI probe which will be used for recovering config space
for SSR and PCI linkdown recovery.

Change-Id: I4fb0db35770d616ad75b8b7329f99fd6a40e9385
CRs-fixed: 2124999
Signed-off-by: Yue Ma <yuem@codeaurora.org>