mm, show_mem: remove SHOW_MEM_FILTER_PAGE_COUNT

mm, show_mem: remove SHOW_MEM_FILTER_PAGE_COUNT

Commit 4b59e6c4 ("mm, show_mem: suppress page counts in non-blockable
contexts") introduced SHOW_MEM_FILTER_PAGE_COUNT to suppress PFN walks on
large memory machines.  Commit c78e9363 (:mm: do not walk all of system
memory during show_mem") avoided a PFN walk in the generic show_mem helper
which removes the requirement for SHOW_MEM_FILTER_PAGE_COUNT in that case.

This patch removes PFN walkers from the arch-specific implementations that
report on a per-node or per-zone granularity.  ARM and unicore32 still do
a PFN walk as they report memory usage on each bank which is a much finer
granularity where the debugging information may still be of use.  As the
remaining arches doing PFN walks have relatively small amounts of memory,
this patch simply removes SHOW_MEM_FILTER_PAGE_COUNT.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: James Bottomley <jejb@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>