KVM: MIPS/T&E: Move CP0 register access into T&E

Access to various CP0 registers via the KVM register access API needs to
be implementation specific to allow restrictions to be made on changes,
for example when VZ guest registers aren't present, so move them all
into trap_emul.c in preparation for VZ.

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

arch/mips/kvm/emulate.c

@@ -1066,7 +1066,7 @@ unsigned int kvm_mips_config4_wrmask(struct kvm_vcpu *vcpu)
 	unsigned int mask = MIPS_CONF_M;
 
 	/* KScrExist */
-	mask |= (unsigned int)vcpu->arch.kscratch_enabled << 16;
+	mask |= 0xfc << MIPS_CONF4_KSCREXIST_SHIFT;
 
 	return mask;
 }