mtd: spi-nor: allow NULL as chip name and try to auto detect it

This will allow spi-nor users to plainly use JEDEC to detect flash chip.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --cc drivers/mtd/spi-nor/spi-nor.c
Simple merge