MAINTAINERS: i8k driver is orphan

Massimo Dal Zotto stopped maintaining the i8k driver several years ago,
so move his name from MAINTAINERS to CREDITS.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Massimo Dal Zotto <dz@debian.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>