PCI: xilinx-nwl: Use irq_data_get_irq_chip_data()

PCI: xilinx-nwl: Use irq_data_get_irq_chip_data()

Going through a full irq descriptor lookup instead of just using the proper
helper function which provides direct access is suboptimal.

In fact it _is_ wrong because the chip callback needs to get the chip data
which is relevant for the chip while using the irq descriptor variant
returns the irq chip data of the top level chip of a hierarchy. It does not
matter in this case because the chip is the top level chip, but that
doesn't make it more correct.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20201210194044.364211860@linutronix.de