phy: usb: Put USB phys into IDDQ on suspend to save power in S2 mode

Currently the Phy driver will put the USB phys into the max
power saving mode (IDDQ) when there is no corresponding XHCI, EHCI
or OHCI client (through rmmod, unbind or if the driver is not
builtin). This change will also put the Phys into IDDQ mode
on suspend so that S2 will get the additional power savings.

Signed-off-by: Al Cooper <alcooperx@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>