mtd: spinand: Fix the error/cleanup path in spinand_init()

The manufacturer specific initialization has already been done when
block unlocking takes place, and if anything goes wrong during this
procedure we should call spinand_manufacturer_cleanup().

Fixes: 7529df46 ("mtd: nand: Add core infrastructure to support SPI NANDs")
Cc: <stable@vger.kernel.org>
Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>