ppc: fix result of DLMZB when no zero bytes are found

It must return 8 and place 8 in XER, but the current code uses
i directly which is 9 at this point of the code.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

target-ppc/int_helper.c

@@ -2556,6 +2556,7 @@ target_ulong helper_dlmzb(CPUPPCState *env, target_ulong high,
         }
         i++;
     }
+    i = 8;
     if (update_Rc) {
         env->crf[0] = 0x2;
     }