KVM: x86 emulator: Use opcode::execute for IN/OUT

IN : E4, E5, EC, ED
OUT: E6, E7, EE, EF

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>