asm-generic: remove ptrace.h

No one is using this header anymore.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Paul Burton <paul.burton@mips.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>