David Engebretsen has moved on to other things and is no longer maintaining
ppc64.  This patch adds an entry in CREDITS to note his contribution in
leading the team that did the PPC64 port originally and updates various
PPC-related MAINTAINERS entries.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>