Staging: dgnc: constify attribute_group structures

Check for attribute_group structures that are only passed as a second
argument to the functions sysfs_remove_group and sysfs_create_group. As
these arguments are constant so, attribute_group structures having this
property  can also be made constant.
Done using coccinelle:

@r1 disable optional_qualifier @
identifier i;
position p;
@@
static struct attribute_group i@p = {...};

@ok1@
identifier r1.i;
position p;
expression e1;
@@
(
sysfs_remove_group(e1,&i@p)
|
sysfs_create_group(e1,&i@p)
)

@bad@
position p!={r1.p,ok1.p};
identifier r1.i;
@@
i@p

@depends on !bad disable optional_qualifier@
identifier r1.i;
@@
static
+const
struct attribute_group i={...};

@depends on !bad disable optional_qualifier@
identifier r1.i;
@@
+const
struct attribute_group i;

File size before:
   text	   data	    bss	    dec	    hex	filename
   6248	   1024	      0	   7272	   1c68
drivers/staging/dgnc/dgnc_sysfs.o

File size after:
   text	   data	    bss	    dec	    hex	filename
   6288	    960	      0	   7248	   1c50
drivers/staging/dgnc/dgnc_sysfs.o

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dgnc/dgnc_sysfs.c

@@ -677,7 +677,7 @@ static struct attribute *dgnc_sysfs_tty_entries[] = {
 	NULL
 };
 
-static struct attribute_group dgnc_tty_attribute_group = {
+static const struct attribute_group dgnc_tty_attribute_group = {
 	.name = NULL,
 	.attrs = dgnc_sysfs_tty_entries,
 };