PCI: layerscape: Use syscon_regmap_lookup_by_phandle_args

Use syscon_regmap_lookup_by_phandle_args() which is a wrapper over
syscon_regmap_lookup_by_phandle() combined with getting the syscon
argument.  Except simpler code this annotates within one line that given
phandle has arguments, so grepping for code would be easier.

Link: https://lore.kernel.org/r/20250112-syscon-phandle-args-pci-v1-2-fcb6ebcc0afc@linaro.org


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Acked-by: Roy Zang <Roy.Zang@nxp.com>