USB: ehci-platform: fix companion-device leak

Make sure do drop the reference taken to the companion device during
resume.

Fixes: d4d75128

 ("usb: host: ehci-platform: fix usb 1.1 device is not connected in system resume")
Cc: stable <stable@vger.kernel.org>     # 4.11
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>