fs/buffer: add folio_set_bh helper

fs/buffer: add folio_set_bh helper

Patch series "convert create_page_buffers to folio_create_buffers".

One of the first kernel panic we hit when we try to increase the block
size > 4k is inside create_page_buffers()[1].  Even though buffer.c
function do not support large folios (folios > PAGE_SIZE) at the moment,
these changes are required when we want to remove that constraint.

This patch (of 4):

The folio version of set_bh_page().  This is required to convert
create_page_buffers() to folio_create_buffers() later in the series.

Link: https://lkml.kernel.org/r/20230417123618.22094-1-p.raghav@samsung.com
Link: https://lkml.kernel.org/r/20230417123618.22094-2-p.raghav@samsung.com
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>