Input: ads7846 - introduce .gpio_pendown to get pendown state

The GPIO connected to ADS7846 nPENIRQ signal is usually used to get
the pendown state as well. Introduce a .gpio_pendown, and use this
to decide the pendown state if .get_pendown_state is NULL.

Signed-off-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

include/linux/spi/ads7846.h

@@ -43,6 +43,9 @@ struct ads7846_platform_data {
 	u16	debounce_tol;		/* tolerance used for filtering */
 	u16	debounce_rep;		/* additional consecutive good readings
 					 * required after the first two */
+	int	gpio_pendown;		/* the GPIO used to decide the pendown
+					 * state if get_pendown_state == NULL
+					 */
 	int	(*get_pendown_state)(void);
 	int	(*filter_init)	(struct ads7846_platform_data *pdata,
 				 void **filter_data);