powerpc/64s: Remove POWER4 support

POWER4 has been broken since at least the change 49d09bf2a6
("powerpc/64s: Optimise MSR handling in exception handling"), which
requires mtmsrd L=1 support. This was introduced in ISA v2.01, and
POWER4 supports ISA v2.00.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kvm/emulate.c

@@ -45,12 +45,6 @@ void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
 #ifdef CONFIG_PPC_BOOK3S
 	/* mtdec lowers the interrupt line when positive. */
 	kvmppc_core_dequeue_dec(vcpu);
-
-	/* POWER4+ triggers a dec interrupt if the value is < 0 */
-	if (vcpu->arch.dec & 0x80000000) {
-		kvmppc_core_queue_dec(vcpu);
-		return;
-	}
 #endif
 
 #ifdef CONFIG_BOOKE