KVM: x86: Explicitly pass an exception struct to check_intercept

Explicitly pass an exception struct when checking for intercept from
the emulator, which eliminates the last reference to arch.emulate_ctxt
in vendor specific code.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>