acpi, nfit: constify *_attribute_group

File size before:
   text	   data	    bss	    dec	    hex	filename
  20792	   1580	    994	  23366	   5b46	drivers/acpi/nfit/core.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
  20968	   1388	    994	  23350	   5b36	drivers/acpi/nfit/core.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

drivers/acpi/nfit/core.c

@@ -1066,7 +1066,7 @@ static struct attribute *acpi_nfit_attributes[] = {
 	NULL,
 };
 
-static struct attribute_group acpi_nfit_attribute_group = {
+static const struct attribute_group acpi_nfit_attribute_group = {
 	.name = "nfit",
 	.attrs = acpi_nfit_attributes,
 	.is_visible = nfit_visible,
@@ -1346,7 +1346,7 @@ static umode_t acpi_nfit_dimm_attr_visible(struct kobject *kobj,
 	return a->mode;
 }
 
-static struct attribute_group acpi_nfit_dimm_attribute_group = {
+static const struct attribute_group acpi_nfit_dimm_attribute_group = {
 	.name = "nfit",
 	.attrs = acpi_nfit_dimm_attributes,
 	.is_visible = acpi_nfit_dimm_attr_visible,
@@ -1640,7 +1640,7 @@ static struct attribute *acpi_nfit_region_attributes[] = {
 	NULL,
 };
 
-static struct attribute_group acpi_nfit_region_attribute_group = {
+static const struct attribute_group acpi_nfit_region_attribute_group = {
 	.name = "nfit",
 	.attrs = acpi_nfit_region_attributes,
 };