ACPI: add 'const' to several ACPI file_operations

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index fd1ba05..5ef885e 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -87,14 +87,14 @@
 	unsigned long pushed;
 };
 
-static struct file_operations acpi_button_info_fops = {
+static const struct file_operations acpi_button_info_fops = {
 	.open = acpi_button_info_open_fs,
 	.read = seq_read,
 	.llseek = seq_lseek,
 	.release = single_release,
 };
 
-static struct file_operations acpi_button_state_fops = {
+static const struct file_operations acpi_button_state_fops = {
 	.open = acpi_button_state_open_fs,
 	.read = seq_read,
 	.llseek = seq_lseek,