blackfin: Add export.h to files using EXPORT_SYMBOL/THIS_MODULE

These particular files were just assuming that module.h was
somehow in the include paths.  Give them the more minimalist
header file explicitly.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/arch/blackfin/kernel/perf_event.c b/arch/blackfin/kernel/perf_event.c
index 04300f2..e47d19a 100644
--- a/arch/blackfin/kernel/perf_event.c
+++ b/arch/blackfin/kernel/perf_event.c
@@ -24,6 +24,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/export.h>
 #include <linux/init.h>
 #include <linux/perf_event.h>
 #include <asm/bfin_pfmon.h>