The register HW_SSP_VERSION is broken for ssp version detection,
as the address of the register is different between imx23 and imx28.
Let's use platform_device_id to detect the device, so that the use
of cpu_is_xxx can be removed.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Acked-by: NChris Ball <cjb@laptop.org>