MAINTAINERS: Add maintainer entry for Ingenic JZ4780 NAND driver

Signed-off-by: Harvey Hunt <harveyhuntnexus@gmail.com>
Cc: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Cc: linux-mtd@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>