KVM: MIPS: Increase KVM_MAX_VCPUS and KVM_USER_MEM_SLOTS to 16

Loongson-3 based machines can have as many as 16 CPUs, and so does
memory slots, so increase KVM_MAX_VCPUS and KVM_USER_MEM_SLOTS to 16.

Reviewed-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Co-developed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-Id: <1590220602-3547-4-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>