powerpc/85xx: Add support for 85xx cpu type detection

Add this file to help detect cpu type in runtime.
These macros will be more favorable for driver
to apply errata and workaround to specified cpu type.

Signed-off-by: Haijun Zhang <Haijun.Zhang@freescale.com>
Signed-off-by: Zhao Chenhui <chenhui.zhao@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>