x86/tools: Standardize output format of insn_decode_test

Standardize warning, error, and success printout format
of insn_decode_test so that user can easily understand
which test tool caused the messages.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/151153628279.22827.4869104298276788693.stgit@devbox


Signed-off-by: Ingo Molnar <mingo@kernel.org>