[POWERPC] Make doc comments extractable

We don't have much in the way of doc comments, but some of those we do have
don't work because they start with "/***" or "/*", not "/**" which is what
kernel-doc requires.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 371973b..2f6f5a7 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -80,7 +80,7 @@
 }
 __setup("savemaxmem=", parse_savemaxmem);
 
-/*
+/**
  * copy_oldmem_page - copy one page from "oldmem"
  * @pfn: page frame number to be copied
  * @buf: target memory address for the copy; this can be in kernel address