pci: layerscape: Add stream_id_cur field to ls_pcie structure

Add stream_id_cur field to ls_pcie structure and initialize
it with 0 for all pcie controllers. This field will be used
for streamId calculation.

Signed-off-by: Wasim Khan <wasim.khan@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>