arch, mm: filter disallowed nodes from arch specific show_mem functions

Architectures that implement their own show_mem() function did not pass
the filter argument to show_free_areas() to appropriately avoid emitting
the state of nodes that are disallowed in the current context.  This patch
now passes the filter argument to show_free_areas() so those nodes are now
avoided.

This patch also removes the show_free_areas() wrapper around
__show_free_areas() and converts existing callers to pass an empty filter.

ia64 emits additional information for each node, so skip_free_areas_zone()
must be made global to filter disallowed nodes and it is converted to use
a nid argument rather than a zone for this use case.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: James Bottomley <jejb@parisc-linux.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/tty/serial/68328serial.c b/drivers/tty/serial/68328serial.c
index d5bfd41..e0a7754 100644
--- a/drivers/tty/serial/68328serial.c
+++ b/drivers/tty/serial/68328serial.c
@@ -281,7 +281,7 @@
 #ifdef CONFIG_MAGIC_SYSRQ
 			} else if (ch == 0x10) { /* ^P */
 				show_state();
-				show_free_areas();
+				show_free_areas(0);
 				show_buffers();
 /*				show_net_buffers(); */
 				return;