uboot-imx

power domain: Add support for multiple powerdomains per device

There are cases where there are more than one power domain
attached to the device inorder to get the device functional.
So add support for enabling power domain based on the index.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>