sparc64 address-congruence property

The Machine Description (MD) property "address-congruence-offset" is
optional. According to the MD specification the value is assumed 0UL when
not present. This caused early boot failure on T5.
Signed-off-by: NBob Picco <bob.picco@oracle.com>
CC: sparclinux@vger.kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/sparc/mm/init_64.c

@@ -1098,7 +1098,14 @@ static int __init grab_mblocks(struct mdesc_handle *md)
 		m->size = *val;
 		val = mdesc_get_property(md, node,
 					 "address-congruence-offset", NULL);
-		m->offset = *val;
+
+		/* The address-congruence-offset property is optional.
+		 * Explicity zero it be identifty this.
+		 */
+		if (val)
+			m->offset = *val;
+		else
+			m->offset = 0UL;
 
 		numadbg("MBLOCK[%d]: base[%llx] size[%llx] offset[%llx]\n",
 			count - 1, m->base, m->size, m->offset);