soc: fsl: qbman: Check if CPU is offline when initializing portals

If the CPU to affine the portal interrupt is offline at boot time
affine the portal interrupt to another online CPU. If the CPU is later
brought online the hotplug handler will correctly adjust the affinity.
Moved common code in a function.

Signed-off-by: Roy Pledge <roy.pledge@nxp.com>
Signed-off-by: Madalin Bucur <madalin.bucur@nxp.com>
Signed-off-by: Li Yang <leoyang.li@nxp.com>