lib/show_mem.c: add cma reserved information

Add cma reserved information which is currently shown as a part of total
reserved only.  This patch is continuation of our previous cma patches
related to this.

  https://lkml.org/lkml/2014/10/20/64
  https://lkml.org/lkml/2014/10/22/383



[akpm@linux-foundation.org: remove hopefully-unneeded ifdefs]
Signed-off-by: Vishnu Pratap Singh <vishnu.ps@samsung.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Pintu Kumar <pintu.k@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>