pseries: Fix compiler warning (conversion of pointer to integral value)

This kind of type cast must use uintptr_t or target_ulong to be portable
for hosts with sizeof(void *) != sizeof(long).

Here the value is assigned to a variable of type target_ulong.
Signed-off-by: NStefan Weil <sw@weilnetz.de>
[agraf: fix compilation on 32bit hosts]
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/ppc/spapr.c

@@ -670,7 +670,7 @@ static void spapr_cpu_reset(void *opaque)
     env->external_htab = spapr->htab;
     env->htab_base = -1;
     env->htab_mask = HTAB_SIZE(spapr) - 1;
-    env->spr[SPR_SDR1] = (unsigned long)spapr->htab |
+    env->spr[SPR_SDR1] = (target_ulong)(uintptr_t)spapr->htab |
         (spapr->htab_shift - 18);
 }