ftide020: add faraday ide ahb controller

Faraday's ftide020_s is an IDE-AHB controller for SoC design.
This patch add the u-boot driver (PIO) of ftide020 ATA (IDE) driver.
IDE commands include read, info, and other functions has been implemented.

Because this IDE controller support AHB interface only which is differ
from other most IDE controller supports PCI interface. Some registers
access is required during CMD/DATA I/O. Hence a configuration
"CONFIG_IDE_AHB" is required to be defined according to the feature in
cmd_ide.c.

Signed-off-by: Macpaul Lin <macpaul@andestech.com>