sh: export return_address() symbol.

This is needed with some of the tracing code built as modules, so provide
the export.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/return_address.c

@@ -9,6 +9,7 @@
  * for more details.
  */
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <asm/dwarf.h>
 
 #ifdef CONFIG_DWARF_UNWINDER
@@ -52,3 +53,5 @@ void *return_address(unsigned int depth)
 }
 
 #endif
+
+EXPORT_SYMBOL_GPL(return_address);