ARM: davinci: dm644x: move private definitions to C file

Move register base addresses and offsets used only by dm644x.c
from arch/arm/mach-davinci/include/mach/dm644x.h to the C file
as these definitions are used only there.

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>