KVM: x86: Fix defines in emulator.c

Unnecassary define was left after commit 7d882ffa ("KVM: x86: Revert
NoBigReal patch in the emulator").

Commit 39f062ff

 ("KVM: x86: Generate #UD when memory operand is required")
was missing undef.

Fix it.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>