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
Bug: 400290767
Bug: 401380274

Change-Id: Ibc11f412964245658cec60af42cf9486adc96e1a
Signed-off-by: Marcus Ma <maminghui5@xiaomi.corp-partner.google.com>
(cherry picked from commit 75c1d11b)
(cherry picked from commit be18f50e)