mtd: spi-nor: Add SR 4bit block protection support

mtd: spi-nor: Add SR 4bit block protection support

Currently we are supporting block protection only for flash chips with
3 block protection bits (BP0-2) in the SR register.

Enable block protection support for flashes with 4 block protection bits
(BP0-3).

Add a flash_info flag for flashes that describe 4 block protection bits.
Add another flash_info flag for flashes in which BP3 bit is not adjacent
to the BP0-2 bits.

Tested with a n25q512ax3 (BP0-3) and w25q128 (BP0-2).

Signed-off-by: Jungseung Lee <js07.lee@samsung.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Tested-by: Michael Walle <michael@walle.cc>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>