Add i.MX7D clk tree support.

Enable all clock to bring up imx7.
Clock framework need be modified a little since imx7d
change clock design. otherwise system will halt and block the
other part upstream.

All clock refine need wait for Dong Aisheng's patch
clk: support clocks which requires parent clock on during operation
Or other solution ready.
Signed-off-by: NAnson Huang <b20788@freescale.com>
Signed-off-by: NAdrian Alonso <aalonso@freescale.com>
Signed-off-by: NFrank Li <Frank.Li@freescale.com>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>