Replace {k,u}probe event argument fetching framework with switch-case based.
Currently that is implemented with structures, macros and chain of
function-pointers, which is more complicated than necessary and may get a
performance penalty by retpoline.

This simplify that with an array of "fetch_insn" (opcode and oprands), and
make process_fetch_insn() just interprets it. No function pointers are used.

Link: http://lkml.kernel.org/r/152465868340.26224.2551120475197839464.stgit@devboxSigned-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>