Remove undocumented set_4byte() call. This was added in commit
5d40b3d384 ("mtd: spi-nor: Add parallel and stacked memories support")
without any explanation in the commit message. Remove it.
Fixes: 5d40b3d384 ("mtd: spi-nor: Add parallel and stacked memories support")
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>