mtd: spi-nor: add a helper to find the spi_device_id

Add the spi_nor_match_id() to find the proper spi_device_id with the
NOR flash's name in the spi_nor_ids table.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>