mtd: spi-nor: Rename CR_QUAD_EN_SPAN to SR2_QUAD_EN_BIT1

JEDEC Basic Flash Parameter Table, 15th DWORD, bits 22:20,
refers to this bit as "bit 1 of the status register 2".
Rename the macro accordingly.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>