input: strict_strtoul takes unsigned long

Fix sparse warning introduced by:
commit 160f1fef7e52e974489b3c70fbd4e094c06965c2 Input: convert drivers to use strict_strtoul()

---
Just noticed this while fixing the lock annotation patch.

 drivers/input/touchscreen/ads7846.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index 77ac820..f695b0b 100644
@@ -472,7 +472,7 @@ static ssize_t ads7846_disable_store(struct device *dev,
 				     const char *buf, size_t count)
 {
 	struct ads7846 *ts = dev_get_drvdata(dev);
-	long i;
+	unsigned long i;
 
 	if (strict_strtoul(buf, 10, &i))
 		return -EINVAL;

1.6.1.rc1.262.gb6810

Applied, thank you Harvey.

Dmitry