ARM i.MX53: Make MX53 EVK bootable

1. Add entries to Kconfig
2. Add machine definition
3. Add Uart platform data, pad setting and base address
4. Adjust GPIO irq number

Signed-off-by: Yong Shen <yong.shen@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>