usb: ohci-platform: Use devm_of_phy_get_by_index

Getting phys by index instead of phy names so that we do
not have to create a naming scheme when multiple phys are present

Signed-off-by: Arun Ramamurthy <arun.ramamurthy@broadcom.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>