drivers: block: Remove the ata_piix driver

This driver was originally added to support the native IDE mode for
Intel chipset, however it has some bugs like not supporting ATAPI
devices, endianness issue, or even broken build when CONFIG_LAB48.
Given no board is using this driver as of today, rather than fixing
all these issues we just remove it from the source tree.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>