PCI: switchtec: Add missing __iomem tag to fix sparse warnings

Fix a missing __iomem tag in the init_pfn() function. This fixes a sparse
warning of the form:

  $ make C=2 drivers/pci/switch/
  drivers/pci/switch/switchtec.c:... incorrect type assignment(different address spaces)

Fixes: 080b47d ("MicroSemi Switchtec management interface driver")
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Logan Gunthorpe <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>

Author: lsgunth

drivers/pci/switch/switchtec.c

@@ -1484,7 +1484,7 @@ static void init_pff(struct switchtec_dev *stdev)
 {
 	int i;
 	u32 reg;
-	struct part_cfg_regs *pcfg = stdev->mmio_part_cfg;
+	struct part_cfg_regs __iomem *pcfg = stdev->mmio_part_cfg;
 
 	for (i = 0; i < SWITCHTEC_MAX_PFF_CSR; i++) {
 		reg = ioread16(&stdev->mmio_pff_csr[i].vendor_id);