nilfs2: replace get_zeroed_page() with kzalloc()

nilfs2: replace get_zeroed_page() with kzalloc()

nilfs_ioctl_wrap_copy() allocates a temporary buffer with
get_zeroed_page().

kzalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.

Replace use of get_zeroed_page() with kzalloc().

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-4-275e36a83f0e@kernel.org
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>