srd: onewire_link/network: Fix annotations, small cleanups.

srd: onewire_link/network: Fix annotations, small cleanups.

The annotation types are 'Text' and 'Warnings', not 'Link' etc. as the
annotations of the onewire_link PD (for example) are already clearly
from the link layer. The annotation types should be different things/formats
of a specific PD's annotation output instead (like "Celsius" / "Kelvin"
for some temperature sensor, for example).