CRIS: UAPI: fix ptrace.h

The exported ptrace.h header on CRIS references an "arch" directory
which does not exist.  Fix this by having the variants in the same
directory and including them conditionally, similar to other
architectures.

Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>