vmlinux.lds.h: remove stale <linux/export.h> include

This is unneeded since commit a6214385 ("vmlinux.lds.h: remove
no-op macro VMLINUX_SYMBOL()").
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

include/asm-generic/vmlinux.lds.h

@@ -54,8 +54,6 @@
 #define LOAD_OFFSET 0
 #endif
 
-#include <linux/export.h>
-
 /* Align . to a 8 byte boundary equals to maximum function alignment. */
 #define ALIGN_FUNCTION()  . = ALIGN(8)