KVM: x86: rename EMULATE_DO_MMIO

The next patch will reuse it for other userspace exits than MMIO,
namely debug events.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --cc arch/x86/include/asm/kvm_host.h
Simple merge

diff --cc arch/x86/kvm/mmu.c
Simple merge

diff --cc arch/x86/kvm/vmx.c
Simple merge

diff --cc arch/x86/kvm/x86.c
Simple merge