CBMEM northbridges: Remove references to global high_tables_base

Use the new helper function set_top_of_ram() to remove remaining
uses of high_tables_base and _size under northbridge/.

Change-Id: I6b0d9615002ed2aff578c5811d7bd43dd2594453
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/3561
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@google.com>
diff --git a/src/northbridge/intel/e7505/northbridge.c b/src/northbridge/intel/e7505/northbridge.c
index 5fbc2e4..a63029b 100644
--- a/src/northbridge/intel/e7505/northbridge.c
+++ b/src/northbridge/intel/e7505/northbridge.c
@@ -85,9 +85,7 @@
 				(remaplimitk + 64*1024) - remapbasek);
 		}
 
-		/* Leave some space for ACPI, PIRQ and MP tables */
-		high_tables_base = (tolmk * 1024) - HIGH_MEMORY_SIZE;
-		high_tables_size = HIGH_MEMORY_SIZE;
+		set_top_of_ram(tolmk * 1024);
 	}
 	assign_resources(dev->link_list);
 }