Input: synaptics-rmi4 - constify attribute_group structures in F01

attribute_groups are not supposed to change at runtime. All functions
working with attribute_groups provided by <linux/sysfs.h> work with const
attribute_group. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   4777	    480	      0	   5257	   1489	drivers/input/rmi4/rmi_f01.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   4817	    416	      0	   5233	   1471	drivers/input/rmi4/rmi_f01.o
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/rmi4/rmi_f01.c

@@ -334,7 +334,7 @@ static struct attribute *rmi_f01_attrs[] = {
 	NULL
 };
 
-static struct attribute_group rmi_f01_attr_group = {
+static const struct attribute_group rmi_f01_attr_group = {
 	.attrs = rmi_f01_attrs,
 };