squashfs: don't call kmalloc in decompressors

squashfs: don't call kmalloc in decompressors

The decompressors may be called while in an atomic section.  So move the
kmalloc() out of this path, and into the "page actor" init function.

This fixes a regression introduced by commit
f268eedddf35 ("squashfs: extend "page actor" to handle missing pages")

Link: https://lkml.kernel.org/r/[email protected]
Fixes: f268eedddf35 ("squashfs: extend "page actor" to handle missing pages")
Reported-by: Chris Murphy <[email protected]>
Signed-off-by: Phillip Lougher <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>