Add support for the I2C-attached Intersil ISL1208 RTC chip.

[akpm@osdl.org: cleanups, fixlets]
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>