ARM: tegra: remove USB address related macros from iomap.h

USB register base address and sizes defined in iomap.h
are not used in any files other than board-dt-tegra20.c.
Hence removed those defines from header file and using
the absolute values in board files.

Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>