x86/platform/intel-mid: Constify mid_pci_platform_pm

This struct never needs to be modified.  The size of pci-mid.o ELF
sections changes thusly:

  -.data          56
  +.data           0
  -.rodata        32
  +.rodata        88
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci-mid.c

@@ -49,7 +49,7 @@ static bool mid_pci_need_resume(struct pci_dev *dev)
 	return false;
 }
 
-static struct pci_platform_pm_ops mid_pci_platform_pm = {
+static const struct pci_platform_pm_ops mid_pci_platform_pm = {
 	.is_manageable	= mid_pci_power_manageable,
 	.set_state	= mid_pci_set_power_state,
 	.choose_state	= mid_pci_choose_state,