auxdisplay: Move clear_display to hd44780_common

This moves the clear_display function from charlcd to hd44780_common.
This is one more step to make charlcd independent from device specific
code. The two hd44780 drivers use the new function from hd44780_common
and charlcd calls this function through its function pointer in its ops
structure.

Reviewed-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Lars Poeschel <poeschel@lemonage.de>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
diff --git a/drivers/auxdisplay/hd44780.c b/drivers/auxdisplay/hd44780.c
index b0893ea..40ea6d2 100644
--- a/drivers/auxdisplay/hd44780.c
+++ b/drivers/auxdisplay/hd44780.c
@@ -129,6 +129,7 @@ static const struct charlcd_ops hd44780_ops_gpio8 = {
 	.print		= hd44780_common_print,
 	.gotoxy		= hd44780_common_gotoxy,
 	.home		= hd44780_common_home,
+	.clear_display	= hd44780_common_clear_display,
 };
 
 /* Send a command to the LCD panel in 4 bit GPIO mode */
@@ -175,6 +176,7 @@ static const struct charlcd_ops hd44780_ops_gpio4 = {
 	.print		= hd44780_common_print,
 	.gotoxy		= hd44780_common_gotoxy,
 	.home		= hd44780_common_home,
+	.clear_display	= hd44780_common_clear_display,
 };
 
 static int hd44780_probe(struct platform_device *pdev)