auxdisplay: constify charlcd_ops.

charlcd_ops are not supposed to change at runtime. All functions
working with charlcd_ops provided by <misc/charlcd.h> work with
const charlcd_ops. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
  12750	    560	    362	  13672	   3568	drivers/auxdisplay/panel.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
  12942	    368	    362	  13672	   3568	drivers/auxdisplay/panel.o

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/auxdisplay/panel.c

@@ -877,21 +877,21 @@ static void lcd_clear_fast_tilcd(struct charlcd *charlcd)
 	spin_unlock_irq(&pprt_lock);
 }
 
-static struct charlcd_ops charlcd_serial_ops = {
+static const struct charlcd_ops charlcd_serial_ops = {
 	.write_cmd	= lcd_write_cmd_s,
 	.write_data	= lcd_write_data_s,
 	.clear_fast	= lcd_clear_fast_s,
 	.backlight	= lcd_backlight,
 };
 
-static struct charlcd_ops charlcd_parallel_ops = {
+static const struct charlcd_ops charlcd_parallel_ops = {
 	.write_cmd	= lcd_write_cmd_p8,
 	.write_data	= lcd_write_data_p8,
 	.clear_fast	= lcd_clear_fast_p8,
 	.backlight	= lcd_backlight,
 };
 
-static struct charlcd_ops charlcd_tilcd_ops = {
+static const struct charlcd_ops charlcd_tilcd_ops = {
 	.write_cmd	= lcd_write_cmd_tilcd,
 	.write_data	= lcd_write_data_tilcd,
 	.clear_fast	= lcd_clear_fast_tilcd,