spi: tegra114: use `spi_transfer_delay_exec` helper

The tegra114 driver has a weird/separate `tegra_spi_transfer_delay()`
function that does 2 delays: one mdelay() and one udelay().

This was introduced via commit f4fade12d5
("spi/tegra114: Correct support for cs_change").

There doesn't seem to be a mention in that commit message to suggest a
specific need/use-case for having the 2 delay calls.
For the most part, udelay() should be sufficient.

This change replaces it with the new `spi_transfer_delay_exec()`, which
should do the same thing.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-11-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-tegra114.c

@@ -984,17 +984,6 @@ static int tegra_spi_setup(struct spi_device *spi)
 	return 0;
 }
 
-static void tegra_spi_transfer_delay(int delay)
-{
-	if (!delay)
-		return;
-
-	if (delay >= 1000)
-		mdelay(delay / 1000);
-
-	udelay(delay % 1000);
-}
-
 static void tegra_spi_transfer_end(struct spi_device *spi)
 {
 	struct tegra_spi_data *tspi = spi_master_get_devdata(spi->master);
@@ -1098,7 +1087,7 @@ static int tegra_spi_transfer_one_message(struct spi_master *master,
 complete_xfer:
 		if (ret < 0 || skip) {
 			tegra_spi_transfer_end(spi);
-			tegra_spi_transfer_delay(xfer->delay_usecs);
+			spi_transfer_delay_exec(xfer);
 			goto exit;
 		} else if (list_is_last(&xfer->transfer_list,
 					&msg->transfers)) {
@@ -1106,11 +1095,11 @@ complete_xfer:
 				tspi->cs_control = spi;
 			else {
 				tegra_spi_transfer_end(spi);
-				tegra_spi_transfer_delay(xfer->delay_usecs);
+				spi_transfer_delay_exec(xfer);
 			}
 		} else if (xfer->cs_change) {
 			tegra_spi_transfer_end(spi);
-			tegra_spi_transfer_delay(xfer->delay_usecs);
+			spi_transfer_delay_exec(xfer);
 		}
 
 	}