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 <[e-mail]>
Acked-by: Julia Lawall <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/dgnc/dgnc_sysfs.c

···
 	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,
 };