mm: remove page_swap_info()

It's more efficient to get the swap_info_struct by calling
swp_swap_info() directly.

Link: https://lkml.kernel.org/r/20231213215842.671461-12-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>