i2c: don't use any __deprecated handling anymore

This can be dropped with commit 771c0353
("deprecate the '__deprecated' attribute warnings entirely and for good")
now in upstream.

And we got rid of the last __deprecated use, too.

Signed-off-by: Sedat Dilek <sedat.dilek@credativ.de>
[wsa: shortened commit message to reflect the current situation]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>