squashfs: pass the inode to squashfs_readahead_fragment()

Patch series "squashfs: Remove page->mapping references".

We're close to being able to kill page->mapping.  These two patches get us
a little bit closer.


This patch (of 2):

Eliminate a reference to page->mapping by passing the inode from the
caller.

Link: https://lkml.kernel.org/r/20250612143903.2849289-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20250612143903.2849289-2-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Phillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>