NTB/msi: Use irq_has_action()

Use the proper core function.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Link: https://lore.kernel.org/r/20201210194044.255887860@linutronix.de