kvm: Move x86-specific functions into target-i386/kvm.c

The functions for checking xcrs, xsave and pit_state2 are
only used on x86, so they should reside in target-i386/kvm.c.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1444933820-6968-1-git-send-email-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>