xics_kvm: fix a build break

On CentOS 7.5, gcc-4.8.5-28.el7_5.1.ppc64le fails to build QEMU due to :

  hw/intc/xics_kvm.c: In function ‘ics_set_kvm_state’:
  hw/intc/xics_kvm.c:281:13: error: ‘ret’ may be used uninitialized in this
    function [-Werror=maybe-uninitialized]
             return ret;

Fix the breakage and also remove the extra error reporting as
kvm_device_access() already provides a substantial error message.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/intc/xics_kvm.c

@@ -186,8 +186,7 @@ static void ics_get_kvm_state(ICSState *ics)
         kvm_device_access(kernel_xics_fd, KVM_DEV_XICS_GRP_SOURCES,
                           i + ics->offset, &state, false, &local_err);
         if (local_err) {
-            error_report("Unable to retrieve KVM interrupt controller state"
-                    " for IRQ %d: %s", i + ics->offset, strerror(errno));
+            error_report_err(local_err);
             exit(1);
         }
 
@@ -273,11 +272,10 @@ static int ics_set_kvm_state(ICSState *ics, int version_id)
                 state |= KVM_XICS_QUEUED;
         }
 
-        kvm_device_access(kernel_xics_fd, KVM_DEV_XICS_GRP_SOURCES,
-                          i + ics->offset, &state, true, &local_err);
+        ret = kvm_device_access(kernel_xics_fd, KVM_DEV_XICS_GRP_SOURCES,
+                                i + ics->offset, &state, true, &local_err);
         if (local_err) {
-            error_report("Unable to restore KVM interrupt controller state"
-                    " for IRQs %d: %s", i + ics->offset, strerror(errno));
+            error_report_err(local_err);
             return ret;
         }
     }