ics932s401: new clock generator chip driver

The ics932s401 is a clock generator chip.  This driver allows users to
read the current clock outputs.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>