powerpc/modules: Create is_module_trampoline()

ftrace has way too much knowledge of our kernel module trampoline
layout hidden inside it. Create is_module_trampoline() that can
abstract this away inside the module loader code.

Signed-off-by: Anton Blanchard <anton@samba.org>
diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h
index c9c7aaa..f2711f0 100644
--- a/arch/powerpc/include/asm/module.h
+++ b/arch/powerpc/include/asm/module.h
@@ -78,6 +78,7 @@
 #    endif	/* MODULE */
 #endif
 
+bool is_module_trampoline(u32 *insns);
 
 struct exception_table_entry;
 void sort_ex_table(struct exception_table_entry *start,