PCI/switchtec: Fix vep_vector_number ioread width

vep_vector_number is actually a 16 bit register which should be read with
ioread16() instead of ioread32().

Fixes: 080b47de ("MicroSemi Switchtec management interface driver")
Link: https://lore.kernel.org/r/20200106190337.2428-3-logang@deltatee.comReported-by: Doug Meyer <dmeyer@gigaio.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/switch/switchtec.c

@@ -1276,7 +1276,7 @@ static int switchtec_init_isr(struct switchtec_dev *stdev)
 	if (nvecs < 0)
 		return nvecs;
 
-	event_irq = ioread32(&stdev->mmio_part_cfg->vep_vector_number);
+	event_irq = ioread16(&stdev->mmio_part_cfg->vep_vector_number);
 	if (event_irq < 0 || event_irq >= nvecs)
 		return -EFAULT;