powerpc/modules: Create is_module_trampoline()

ftrace has way too much knowledge of our kernel module trampoline
layout hidden inside it. Create is_module_trampoline() that can
abstract this away inside the module loader code.

Signed-off-by: Anton Blanchard <anton@samba.org>
powerpc/modules: Create module_trampoline_target()

ftrace has way too much knowledge of our kernel module trampoline
layout hidden inside it. Create module_trampoline_target() that gives
the target address of a kernel module trampoline.

Signed-off-by: Anton Blanchard <anton@samba.org>
powerpc/ftrace: Use module loader helpers to parse trampolines

Now we have is_module_trampoline() and module_trampoline_target()
we can remove a bunch of intimate kernel module trampoline
knowledge from ftrace.

Signed-off-by: Anton Blanchard <anton@samba.org>