xtensa: drop unneeded platform/hardware.h headers

platform/hardware.h no longer supply any information for processor.h,
vectors.h, setup.c or vmlinux.lds.S, don't include it.
This header is now empty in the platforms/iss, so remove it altogether.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
5 files changed