spapr: Enable in-kernel H_SET_MODE handling

For setting debug watchpoints, sPAPR guests use H_SET_MODE hypercall.
The existing QEMU H_SET_MODE handler does not support this but
the KVM handler in HV KVM does. However it is not enabled.

This enables the in-kernel H_SET_MODE handler which handles:
- Completed Instruction Address Breakpoint Register
- Watch point 0 registers.

The rest is still handled in QEMU.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -1546,6 +1546,7 @@ static void ppc_spapr_init(MachineState *machine)
     if (kvm_enabled()) {
         /* Enable H_LOGICAL_CI_* so SLOF can talk to in-kernel devices */
         kvmppc_enable_logical_ci_hcalls();
+        kvmppc_enable_set_mode_hcall();
     }
 
     /* allocate RAM */