mtd: spi-nor: macronix: Add support for mx25u51245g

mx25u51245g is a mass production for new design and
replace mx66u51235f(phase out).

Validated by read, erase, read back, write and read back
on Xilinx Zynq PicoZed FPGA board which included
Macronix SPI Host (driver/spi/spi-mxic.c).

Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>