memory: atmel-ebi: move NUM_CS definition inside EBI driver

The total number of EBI CS lines is described by the EBI controller
and not by the Matrix. Move the definition for the number of CS
inside EBI driver.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20190906150632.19039-1-tudor.ambarus@microchip.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>