sparc: add export.h to arch/sparc files as required

These files are only exporting symbols, so they don't need
the full module.h header file.  Previously they were getting
access to EXPORT_SYMBOL implicitly via overuse of module.h
from within other .h files, but that is being cleaned up.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/arch/sparc/mm/highmem.c b/arch/sparc/mm/highmem.c
index 4730eac..77140a0 100644
--- a/arch/sparc/mm/highmem.c
+++ b/arch/sparc/mm/highmem.c
@@ -24,6 +24,7 @@
  */
 #include <linux/mm.h>
 #include <linux/highmem.h>
+#include <linux/export.h>
 #include <asm/pgalloc.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>