phy: qcom-usb-hs: Fix unbalanced notifier registration

Phy power on/off cycle can happen several times during device life.
We then need to balance the extcon notifier registration accordingly.

LKML: https://patchwork.kernel.org/patch/10587509/



Fixes: f0b5c2c9 ("phy: qcom-usb-hs: Replace the extcon API")
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>