spapr: Plug minor memory leak in spapr_machine_init()

spapr_machine_init() leaks an Error object when
kvmppc_check_papr_resize_hpt() fails and spapr->resize_hpt is
SPAPR_RESIZE_HPT_DISABLED, i.e. when the host doesn't support hash
page table resizing, and the user didn't ask for it.  As harmless as
memory leaks can possibly be.  Plug it.

Fixes: 30f4b05bd0
Cc: David Gibson <dgibson@redhat.com>
Cc: qemu-ppc@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20200630090351.1247703-8-armbru@redhat.com>

hw/ppc/spapr.c

@@ -2731,6 +2731,7 @@ static void spapr_machine_init(MachineState *machine)
         error_report_err(resize_hpt_err);
         exit(1);
     }
+    error_free(resize_hpt_err);
 
     spapr->rma_size = spapr_rma_size(spapr, &error_fatal);