csky: Add non-uapi asm/ptrace.h namespace

Move #ifdef __KERNEL__ code in the uapi namespace to non-uapi
include/asm/ptrace.h namespace and remove #ifdef __KERNEL__ in
include/asm/ptrace.h. Seperate ptrace.h in uapi and non-uapi is more
common and clear.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Dmitry V. Levin <ldv@altlinux.org>