iio: ad9523: Fix displayed phase

Fix the displayed phase for the ad9523 driver. Currently the most
significant decimal place is dropped and all other digits are shifted one
to the left. This is due to a multiplication by 10, which is not necessary,
so remove it.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Fixes: cd1678f9 ("iio: frequency: New driver for AD9523 SPI Low Jitter Clock Generator")
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>