staging: dgnc: Constify ktermios structure

The ktermios structure is a local default termios struct. All ports
are initially created with this termios. Since, the structure is
never modified, it can be declared as const.

Coccinelle Script:
@r disable optional_qualifier@
identifier s,i;
position p;
@@
static struct ktermios i@p = { ... };

@ok1@
identifier r.i;
expression e;
position p;
@@
e = i@p

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

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

File Size before:

text	data   bss   dec    hex	  filename
25469	2048   256   27773  6c7d  drivers/staging/dgnc/dgnc_tty.o

File Size after:

text	data	bss	dec	hex	filename
25636	2016	256	27908	6d04	drivers/staging/dgnc/dgnc_tty.o

Signed-off-by: Gargi Sharma <gs051095@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>