hwmon: applesmc: add support for iMac 5

Add temperature sensor support for iMac 5.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Tested-by: Ricky Campbell <johnrcampbell@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>