mtd: spi-nor: remove NO_CHIP_ERASE flag

There's no flash using it and we'd like to rely instead on SFDP data,
thus remove it.

Tested-by: Fabio Estevam <festevam@denx.de>
Link: https://lore.kernel.org/r/20231125123529.55686-5-tudor.ambarus@linaro.org


Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>