mtd: nand: tango: Fix incorrect use of SEQIN command

SEQIN is supposed to be used when one wants to start programming a page.
What we want here is just to change the column within the page, which is
done with the RNDIN command.

Fixes: 6956e238 ("mtd: nand: add tango NAND flash controller support")
Cc: stable@vger.kernel.org
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>