i2c: use bcd2bin/bin2bcd

Change i2c to use the new bcd2bin/bin2bcd functions instead of the
obsolete BCD2BIN/BIN2BCD macros.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>