mtd: spi-nor: add hisilicon spi-nor flash controller driver

Add hisilicon spi-nor flash controller driver

Signed-off-by: Binquan Peng <pengbinquan@hisilicon.com>
Signed-off-by: Jiancheng Xue <xuejiancheng@hisilicon.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Reviewed-by: Jagan Teki <jteki@openedev.com>
Reviewed-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>