Adding ehci clock enabling mechanism part of clock framework.
When essential clocks are enabled during init phase usb host
clocks can also be enabled from clock framework.
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Tested-by: Stefano Babic <sbabic@denx.de>