modules: mark each_symbol_section static

commit a54e04914c211b5678602a46b3ede5d82ec1327d upstream.

each_symbol_section is only used inside of module.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>