iio-light: Use a signed return type for ltr501_match_samp_freq()

Author: Markus Elfring <elfring@users.sourceforge.net>

The return type "unsigned int" was used by the ltr501_match_samp_freq()
function despite of the aspect that it will eventually return a negative
error code.
Improve this implementation detail by deletion of the type modifier then.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring 
Acked-by: Peter Meerwald-Stadler 
Signed-off-by: Jonathan Cameron 
 drivers/iio/light/ltr501.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iio/light/ltr501.c b/drivers/iio/light/ltr501.c
index 809a961..6bf89d8 100644
--- a/drivers/iio/light/ltr501.c
+++ b/drivers/iio/light/ltr501.c
@@ -180,7 +180,7 @@ static const struct ltr501_samp_table ltr501_ps_samp_table[] = {
 			{500000, 2000000}
-static unsigned int ltr501_match_samp_freq(const struct ltr501_samp_table *tab,
+static int ltr501_match_samp_freq(const struct ltr501_samp_table *tab,
 					   int len, int val, int val2)
 	int i, freq;