cmn600: Fix incorrect cache group count calculation
The CMN-600 module currently incorrectly calculates the HN-F cache group count for HN-F counts less than the number of HN-F entries per HN-F cache group.
Change-Id: If840a78b8b70b1eb8b2b77768f4e95c0d8c369b3 Signed-off-by: Chris Kay chris.kay@arm.com