mtd: spi-nor: macronix: Add support for mx25l51245g

mx25l51245g is a mass production for new design and
replace mx66l51235l(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>