x86/ftrace: Do not jump to direct code in created trampolines

When creating a trampoline based on the ftrace_regs_caller code, nop out the
jnz test that would jmup to the code that would return to a direct caller
(stored in the ORIG_RAX field) and not back to the function that called it.

Link: http://lkml.kernel.org/r/20200422162750.638839749@goodmis.org



Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>