ARM: imx: add VF610 clock support

Add clock support for Vybrid VF610. It uses dtc macro support to
define all clock IDs in vf610-clock.h to keep clock IDs coherence
between kernel and DT.

Signed-off-by: Jingchang Lu <b35083@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>