Input: ads7846 - use new delay structure for SPI transfer delays

In a recent change to the SPI subsystem [1], a new `delay` struct was added
to replace the `delay_usecs`. This change replaces the current
`delay_usecs` with `delay` for this driver.

The `spi_transfer_delay_exec()` function [in the SPI framework] makes sure
that both `delay_usecs` & `delay` are used (in this order to preserve
backwards compatibility).

[1] commit bebcfd2 ("spi: introduce `delay` field for
`spi_transfer` + spi_transfer_delay_exec()")

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20191210141103.15910-1-alexandru.ardelean@analog.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/ads7846.c

@@ -333,7 +333,8 @@ static int ads7846_read12_ser(struct device *dev, unsigned command)
 		req->xfer[1].len = 2;
 
 		/* for 1uF, settle for 800 usec; no cap, 100 usec.  */
-		req->xfer[1].delay_usecs = ts->vref_delay_usecs;
+		req->xfer[1].delay.value = ts->vref_delay_usecs;
+		req->xfer[1].delay.unit = SPI_DELAY_UNIT_USECS;
 		spi_message_add_tail(&req->xfer[1], &req->msg);
 
 		/* Enable reference voltage */
@@ -1018,7 +1019,8 @@ static void ads7846_setup_spi_msg(struct ads7846 *ts,
 	 * have had enough time to stabilize.
 	 */
 	if (pdata->settle_delay_usecs) {
-		x->delay_usecs = pdata->settle_delay_usecs;
+		x->delay.value = pdata->settle_delay_usecs;
+		x->delay.unit = SPI_DELAY_UNIT_USECS;
 
 		x++;
 		x->tx_buf = &packet->read_y;
@@ -1061,7 +1063,8 @@ static void ads7846_setup_spi_msg(struct ads7846 *ts,
 
 	/* ... maybe discard first sample ... */
 	if (pdata->settle_delay_usecs) {
-		x->delay_usecs = pdata->settle_delay_usecs;
+		x->delay.value = pdata->settle_delay_usecs;
+		x->delay.unit = SPI_DELAY_UNIT_USECS;
 
 		x++;
 		x->tx_buf = &packet->read_x;
@@ -1094,7 +1097,8 @@ static void ads7846_setup_spi_msg(struct ads7846 *ts,
 
 		/* ... maybe discard first sample ... */
 		if (pdata->settle_delay_usecs) {
-			x->delay_usecs = pdata->settle_delay_usecs;
+			x->delay.value = pdata->settle_delay_usecs;
+			x->delay.unit = SPI_DELAY_UNIT_USECS;
 
 			x++;
 			x->tx_buf = &packet->read_z1;
@@ -1125,7 +1129,8 @@ static void ads7846_setup_spi_msg(struct ads7846 *ts,
 
 		/* ... maybe discard first sample ... */
 		if (pdata->settle_delay_usecs) {
-			x->delay_usecs = pdata->settle_delay_usecs;
+			x->delay.value = pdata->settle_delay_usecs;
+			x->delay.unit = SPI_DELAY_UNIT_USECS;
 
 			x++;
 			x->tx_buf = &packet->read_z2;