Revert "module: Add retpoline tag to VERMAGIC"

This reverts commit 6cfb521a.

Turns out distros do not want to make retpoline as part of their "ABI",
so this patch should not have been merged.  Sorry Andi, this was my
fault, I suggested it when your original patch was the "correct" way of
doing this instead.

Reported-by: Jiri Kosina <jikos@kernel.org>
Fixes: 6cfb521a ("module: Add retpoline tag to VERMAGIC")
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: rusty@rustcorp.com.au
Cc: arjan.van.de.ven@intel.com
Cc: jeyu@kernel.org
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>