iio: Reject trailing garbage when parsing fixed point numbers

When parsing a fixed point number IIO stops parsing the string once it has
reached the last requested decimal place. This means that the remainder of the
string is silently accepted regardless, of whether it is part of a valid number
or not. This patch modifies the code to scan the whole string and only accept
valid numbers. Since fract_mult is 0 after the last decimal place any digit that
may follows won't affect the result.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/industrialio-core.c

@@ -445,8 +445,6 @@ static ssize_t iio_write_channel_info(struct device *dev,
 				integer = integer*10 + *buf - '0';
 			else {
 				fract += fract_mult*(*buf - '0');
-				if (fract_mult == 1)
-					break;
 				fract_mult /= 10;
 			}
 		} else if (*buf == '\n') {