ARM: davinci: dm646x: move private definitions to C file

Move register base addresses and offsets used only in dm646x.c
from arch/arm/mach-davinci/include/mach/dm646x.h in to the C
file as these definitions are used only in C file.

This helps reduce code in arch/arm/mach-davinci/include/mach/
which is not really needed by rest of the kernel.

Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>