mtd: spi-nor: Rework the SPI NOR lock/unlock logic

Add the SNOR_F_HAS_LOCK flag and set it when SPI_NOR_HAS_LOCK is set
in the flash_info entry or when it's a Micron or ST flash.

Move the locking hooks in a separate struct so that we have just
one field to update when we change the locking implementation.

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
[tudor.ambarus@microchip.com: use ->default_init() hook, introduce
spi_nor_late_init_params(), set ops in nor->params]
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>