ENGR00154922 [MX6]Disable some clocks during boot

ENGR00154922 [MX6]Disable some clocks during boot

To save power, we should disable as much as possible
when kernel boot up, only leaving the necessary clocks
on, devices should enable their clock in init.This is
necessary for our MX6q, or the chip will be too hot,
may damage.

After doing this change, we can save more than 150mA@5V.

Signed-off-by: Anson Huang <b20788@freescale.com>