[POWERPC] dont allow pSeries_probe to succeed without initialising MMU

pSeries_probe can decide that we are a pseries but then fail to
initialise the MMU. If an rtas node doesnt exist, we continually fall
out of pSeries_probe_hypertas early and never get to the MMU init code.

While pseries without RTAS is an illegal combination, the way we
currently fail is a pain to track down, and can happen if your flattened
device tree code has issues (like mine did :).

With the following patch we init the MMU, come up and print some
warnings about RTAS not existing, instead of looping on 0x400 exceptions.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/pseries/setup.c

@@ -422,11 +422,6 @@ static int __init pSeries_probe_hypertas(unsigned long node,
 	if (of_get_flat_dt_prop(node, "ibm,hypertas-functions", NULL) != NULL)
  		powerpc_firmware_features |= FW_FEATURE_LPAR;
 
-	if (firmware_has_feature(FW_FEATURE_LPAR))
-		hpte_init_lpar();
-	else
-		hpte_init_native();
-
  	return 1;
 }
 
@@ -452,6 +447,11 @@ static int __init pSeries_probe(void)
 	/* Now try to figure out if we are running on LPAR */
 	of_scan_flat_dt(pSeries_probe_hypertas, NULL);
 
+	if (firmware_has_feature(FW_FEATURE_LPAR))
+		hpte_init_lpar();
+	else
+		hpte_init_native();
+
 	DBG("Machine is%s LPAR !\n",
 	    (powerpc_firmware_features & FW_FEATURE_LPAR) ? "" : " not");