Preparing for Loongson-3 virtualization, add KVM target support for
MIPS64 in configure script.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Co-developed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reviewed-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Signed-off-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Message-Id: <1588501221-1205-2-git-send-email-chenhc@lemote.com>