adt7462: new hwmon driver

New driver to play with.  As Jean mentioned a couple of years ago, this
chip is a beast with odd combinations of 8 fans, 4 temperatures, and 13
voltage sensors.  This driver has been tested on an IntelliStation Z30.

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>