HID: make device_attribute const

Make this const as it is only passed as an argument to the function
device_create_file and device_remove_file and the corresponding arguments are
of type const.  Done using Coccinelle
Signed-off-by: NBhumika Goyal <bhumirks@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

drivers/hid/hid-core.c

@@ -1662,7 +1662,7 @@ static struct bin_attribute dev_bin_attr_report_desc = {
 	.size = HID_MAX_DESCRIPTOR_SIZE,
 };
 
-static struct device_attribute dev_attr_country = {
+static const struct device_attribute dev_attr_country = {
 	.attr = { .name = "country", .mode = 0444 },
 	.show = show_country,
 };