This simplifies things and allows idling both MUSB and PHY
when nothing is configured. Let's just return early from PM
runtime if musb is not yet initialized.

Let's also warn if PHY is not configured.
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NBin Liu <b-liu@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>