modules: Drop the .export_symbol section from the final modules

Commit ddb5cdba ("kbuild: generate KSYMTAB entries by modpost")
forget drop the .export_symbol section from the final modules.

Fixes: ddb5cdba ("kbuild: generate KSYMTAB entries by modpost")
Signed-off-by: Wang Yao <wangyao@lemote.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/module.lds.S

@@ -13,6 +13,7 @@ SECTIONS {
 	/DISCARD/ : {
 		*(.discard)
 		*(.discard.*)
+		*(.export_symbol)
 	}
 
 	__ksymtab		0 : { *(SORT(___ksymtab+*)) }