mtd: spi-nor-ids: add Macronix mx25u51245g flash entry

Add Macronix mx25u51245g flash entry, so this can be used on
SoCFPGA devices.

Signed-off-by: Tien Fong Chee <tien.fong.chee@intel.com>
[Jagan: updated commit head]
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>