mm: Map most files to use export.h instead of module.h

The files changed within are only using the EXPORT_SYMBOL
macro variants.  They are not using core modular infrastructure
and hence don't need module.h but only the export.h header.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/mm/truncate.c b/mm/truncate.c
index b40ac6d..632b15e 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -12,7 +12,7 @@
 #include <linux/gfp.h>
 #include <linux/mm.h>
 #include <linux/swap.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/pagemap.h>
 #include <linux/highmem.h>
 #include <linux/pagevec.h>