phy: qcom-usb-hs: Fix extcon double register after power cycle

Commit f0b5c2c9 ("phy: qcom-usb-hs: Replace the extcon API")
switched from extcon_register_notifier() to the resource-managed
API, i.e. devm_extcon_register_notifier().

This is problematic in this case, because the extcon notifier
is dynamically registered/unregistered whenever the PHY is powered
on/off. The resource-managed API does not unregister the notifier
until the driver is removed, so as soon as the PHY is power cycled,
attempting to register the notifier again results in:

	double register detected
	WARNING: CPU: 1 PID: 182 at kernel/notifier.c:26 notifier_chain_register+0x74/0xa0
	Call trace:
	 ...
	 extcon_register_notifier+0x74/0xb8
	 devm_extcon_register_notifier+0x54/0xb8
	 qcom_usb_hs_phy_power_on+0x1fc/0x208
	 ...

... and USB stops working after plugging the cable out and in
another time.

The easiest way to fix this is to make a partial revert of
commit f0b5c2c9 ("phy: qcom-usb-hs: Replace the extcon API")
and avoid using the resource-managed API in this case.

Fixes: f0b5c2c9

 ("phy: qcom-usb-hs: Replace the extcon API")
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>