Reduce duplicate definition in CAR code.

Reduce duplicate definition in CAR code.

Macros for the register addresses for the MTRR MSRs are already defined
in include/cpu/x86/car.h. This patch uses those macros instead of
creating a second instance of that same data.

I also added a few macros to the amd mtrr.h to make the MSR naming more
consistent.

Signed-off-by: Warren Turkal <wt@penguintechs.org>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5942 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1