net: cnss2: reuse the memory for pci_priv

The memory of 'pci_priv' is malloced when PCI power up,
and it's not freed when PCI power down, though it will
be finally freed when PCI device destroyed, but it will
cause memory consumption accumulates if continuously do
'power up' and 'power down'.

So reuse the memory if it's already malloced to avoid
the potential issue.

Change-Id: I9375a689295a462f930911237c22df5a36ce0dbc
Signed-off-by: Miaoqing Pan <quic_miaoqing@quicinc.com>