Set the default VCPU state closer to the architectural reset state, with
PC pointing at the reset vector (uncached PA 0x1fc00000, which for KVM
T&E is VA 0x5fc00000), and with CP0_Status.BEV and CP0_Status.ERL to 1.

Although QEMU at least will overwrite this state, it makes sense to do
this now that CP0_EBase is properly implemented to check BEV, and now
that we support a sparse GPA layout potentially with a boot ROM at GPA
0x1fc00000.
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