ppc4xx: Cleanup some HW register names

Here you find all the changes in the include directory for new register names
and adapting other ones to the names used by AMCC in their manuals, e.g.
For 440EPx/GRPPC440EPx/GRX, Revision 1.15 – September 22, 2008
For PPC405GP Embedded Processor, Revision 1.02 – March 22, 2006

Signed-off-by: Niklaus Giger <niklaus.giger@member.fsf.org>
Signed-off-by: Stefan Roese <sr@denx.de>