mtd: spi-nor: core: Fix spi_nor_flash_parameter otp description

Update the description of the otp member of the
struct spi_nor_flash_parameter.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20211029172633.886453-2-tudor.ambarus@microchip.com