spapr: fix off-by-one error in spapr_ovec_populate_dt()

The last byte of the option vector was missing due to an off-by-one
error. Without this fix, client architecture support negotiation will
fail because the last byte of option vector 5, which contains the MMU
support, will be missed.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
(cherry picked from commit fe93e3e6ec1b1bf4a4c9d4bf55f8776318da6847)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
diff --git a/hw/ppc/spapr_ovec.c b/hw/ppc/spapr_ovec.c
index 3eb1d59..0bcf311 100644
--- a/hw/ppc/spapr_ovec.c
+++ b/hw/ppc/spapr_ovec.c
@@ -250,5 +250,5 @@
         }
     }
 
-    return fdt_setprop(fdt, fdt_offset, name, vec, vec_len);
+    return fdt_setprop(fdt, fdt_offset, name, vec, vec_len + 1);
 }