perf/smmuv3: Use msi_get_virq()

Let the core code fiddle with the MSI descriptor retrieval.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20211210221815.029143589@linutronix.de