soc/fsl/qbman: Rework QBMan private memory setup

Rework QBMan private memory setup so that the areas are not
zeroed if the device was previously initialized

If the QMan private memory was already initialized skip the PFDR
initialization.

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