i2c: algos: bit: make the error messages grepable

Yep, I went looking for one of these, and I wasn't able to find it
easily.  That's worse than a line which is 82-chars long, IMHO.

Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>