mtd: nand_h1900 never worked

This driver has been broken through all of git history and
cannot even be built. Better mark it as broken. Next stop is
removing from the tree.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>