s390/pci: Use irq_data_get_msi_desc()

No point in doing another lookup of irq_data, it's already provided as
an argument.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Link: https://lore.kernel.org/linux-s390/8735aoui07.ffs@tglx/


[agordeev@linux.ibm.com added Link tag]
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>