remove asm-generic/ptrace.h v2

[Christoph Hellwig]

Hi all,

asm-generic/ptrace.h is a little weird in that it doesn't actually
implement any functionality, but it provided multiple layers of macros
that just implement trivial inline functions.  We implement those
directly in the few architectures and be off with a much simpler
design.

Changes since v1:
 - add a missing empty line between functions