iio: pressure: ms5611: remove IIO_CHAN_INFO_SCALE from mask

IIO_CHAN_INFO_SCALE is useful whenever conversion to standard units is done
in userspace. In this case conversion is handled by driver so this bit
is unnecessary.

Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>