llog: add direct log helpers

llog: add direct log helpers

Sometimes, the parent object might not be available so we need to pass in
the log-object directly. Use "d" as prefix for those functions and add
variants for the most oftenly used functions.

If you need more direct variants, add them when you introduce the first
user.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>