KVM: x86 emulator: Clean up INT n/INTO/INT 3(CC/CD/CE)

Call emulate_int() directly to avoid spaghetti goto's.

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