mtd: rawnand: Add Macronix raw NAND controller driver

Add a driver for Macronix raw NAND controller.

This patch referred from linux mxic_nand.c. The difference from the
linux version is described here.

1. In order to adapt to the uboot nand framework, add function
   binding (cmdfunc, read_byte, read_buf, write_buf).

2. Added parsing command format to use hardware correctly.

3. Remove the incompatible functions of Uboot.

Signed-off-by: Zhengxun Li <zhengxunli@mxic.com.tw>