phy: cpcap-usb: Fix flakey host idling and enumerating of devices

We must let the USB host idle things properly before we switch to debug
UART mode. Otherwise the USB host may never idle after disconnecting
devices, and that causes the next enumeration to be flakey.

Cc: Jacopo Mondi <jacopo@jmondi.org>
Cc: Marcel Partap <mpartap@gmx.net>
Cc: Merlijn Wajer <merlijn@wizzup.org>
Cc: Michael Scott <hashcode0f@gmail.com>
Cc: NeKit <nekit1000@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Sebastian Reichel <sre@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Fixes: 6d6ce40f ("phy: cpcap-usb: Add CPCAP PMIC USB support")
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>