PCI: acpiphp_ibm: Make ibm_apci_table_attr __ro_after_init

ibm_apci_table_attr is not modified after being initialized by
ibm_acpiphp_init(). It is passed as an argument to the functions
sysfs_{remove/create}_bin_file(), but both the arguments are const.
Add __ro_after_init to its declaration.

[bhelgaas: changelog]
Signed-off-by: Bhumika Goyal <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>

drivers/pci/hotplug/acpiphp_ibm.c

···
 
 static acpi_handle ibm_acpi_handle;
 static struct notification ibm_note;
-static struct bin_attribute ibm_apci_table_attr = {
+static struct bin_attribute ibm_apci_table_attr __ro_after_init = {
 	    .attr = {
 		    .name = "apci_table",
 		    .mode = S_IRUGO,