ANDROID: swapfile: Add EXPORT_SYMBOL_GPL for page_swap_info

We present a specific requirement regarding the memory management
and I/O operations.In our project,we're focused on handling scenarios
where I/O delays are triggered by anoymous pages.During this period,we
need to obtain swap_info_struct according to page to obtain the
corresponding block device id.

Bug: 397308736

Change-Id: Ibc11f412964245658cec60af42cf9486adc96e1a
Signed-off-by: Marcus Ma <maminghui5@xiaomi.corp-partner.google.com>

mm/swapfile.c

@@ -3431,6 +3431,7 @@ struct swap_info_struct *page_swap_info(struct page *page)
 	swp_entry_t entry = { .val = page_private(page) };
 	return swp_swap_info(entry);
 }
+EXPORT_SYMBOL_GPL(page_swap_info);
 
 /*
  * out-of-line methods to avoid include hell.