KVM: MIPS: Override HVA error values for EVA

MIPS Enhanced Virtual Addressing (EVA) allows the user mode and kernel
mode address spaces to overlap, breaking the assumption that PAGE_OFFSET
is an appropriate KVM HVA error value, since PAGE_OFFSET may be as low
as zero.

Fix this in the same way that s390 does in commit bf640876e21f ("KVM:
s390: Make KVM_HVA_ERR_BAD usable on s390"), by overriding
KVM_HVA_ERR_[RO_]BAD and kvm_is_error_hva() in asm/kvm_host.h.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org