mtd: spi-nor: macronix: Add support for MX25R1635F

The MX25R1635F is the smaller sibling of the MX25R3235F that is
already supported. It's only half the size (16Mb).

It was tested on the Kontron Electronics i.MX8MM SoM (N8010)
using raw read and write from and to the mtd device and
the 'flash_erase' command.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
[tudor.ambarus@microchip.com: update subject]
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20200702140523.6811-1-frieder.schrempf@kontron.de