mm/migrate: convert isolate_movable_page() to use folios

Removes 6 calls to compound_head() and prepares the function to take in a
folio instead of page argument.

Link: https://lkml.kernel.org/r/20230130214352.40538-4-vishal.moola@gmail.com


Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>