staging: iio: adc: mxs-lradc: Change type in printf format string

Wrong type in printf format string, requires 'int'
but the argument type is 'unsigned int'

This was found using a static code analysis program called cppcheck

Signed-off-by: Rickard Strandqvist <[e-mail]>
Reviewed-by: Marek Vasut <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/staging/iio/adc/mxs-lradc.c

···
 	int i, len = 0;
 
 	for (i = 0; i < ARRAY_SIZE(lradc->scale_avail[ch]); i++)
-		len += sprintf(buf + len, "%d.%09u ",
+		len += sprintf(buf + len, "%u.%09u ",
 			       lradc->scale_avail[ch][i].integer,
 			       lradc->scale_avail[ch][i].nano);