lm85: support adt7468 chips

The adt7468 is a follow-on to the adt7463, so plumb in adt7468 support
along the same code paths.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
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>