Revert "x86/bugs: Use fixed addressing for VERW operand"

This was reverts commit 8009479e.

It was originally in x86/urgent, but was deemed wrong so got zapped.
But in the meantime, x86/urgent had been merged into x86/apic to
resolve a conflict.  I didn't notice the merge so didn't zap it
from x86/apic and it managed to make it up with the x86/apic
material.

The reverted commit is known to cause some KASAN problems.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>