iio:frequency:admv1013: White space cleanup of spacing around {} in id tables

The spacing was inconsistent with a space after the { but not
before the }. Tidy this up to avoid providing a bad example to copy into
new drivers.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Antoniu Miclaus <antoniu.miclaus@analog.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Link: https://lore.kernel.org/r/20211230174911.78291-11-jic23@kernel.org