adt74{62, 70, 73}: Use DIV_ROUND_CLOSEST for rounded division

Modify some hwmon drivers to use DIV_ROUND_CLOSEST instead of bloating
source with (naughty) macros.

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>