mtd: spi-nor: intel: remove global protection flag

For the Atmel and SST parts this flag was already moved to individual
flash parts because it is considered bad esp. because newer flash chips
will automatically inherit the "has locking" support. While this won't
likely be the case for the Intel parts, we do it for consistency
reasons.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20201203162959.29589-6-michael@walle.cc