usb: phy: fsl: Fix build errors

commit e47d9254 (usb: move the OTG state from
the USB PHY to the OTG structure) moved the
OTG state from struct usb_phy to struct usb_otg.

Unfortunately, even though I fixed quite a few
build regressions with that patch already, this
one was still missing.

Note that this driver still has other randconfig
build problems which I'll leave for driver author
to fix, as that's less trivial.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>