phy: twl4030-usb: Fix for musb session bit based PM

Now with musb driver implementing generic session bit based
PM, we need to have the USB PHYs behaving in a sane way for
platforms implementing PM.

Currently twl4030-usb enables PM in twl4030_phy_power_on()
and then disables it in twl4030_phy_power_off(). This will
block PM runtime for the SoC when no cable is connected.

Fix the issue by moving PM runtime autosuspend call to
happen where it gets called in twl4030_phy_power_on().

Note that this patch should not be backported to anything
before commit 467d5c98 ("usb: musb: Implement session bit
based runtime PM for musb-core") as before that all the
glue layers implemented their own PM.

Fixes: 467d5c98 ("usb: musb: Implement session bit based
runtime PM for musb-core")
Tested-by: Ladislav Michl <ladis@linux-mips.org>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>