x86: conga-qeval20-qa3: Add SMBus support and SMSC2513 config code

This patch includes the following changes:

- Remove Designware I2C support from dts as its not used
- Configure SMBus PADs in dts
- Enable I2C commands and I2C support
- Configure SMSC2513 USB hub via SMBus upon startup
- Move environment location to match Minnowmax example
- Enhancement of the default environment

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>