msm: gpio-usbdetect: Use extcon_set_property to notify speed

The 4.9 kernel uses extcon_set_property to notify
the USB speed. Update the driver to use it.

Change-Id: I84a1997d69e77666f0668657b3ecbfd9c93a6913
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>