usb: ehci: Fix HSIC controller autosuspend

When the HSIC peripheral is disconnected, its platform device is
removed via platform_device_del(), which increments the PM
disable_depth counter. The EHCI driver's remove callback is
additionally calling pm_runtime_disable() which increments the
counter again. When the peripheral is reconnected via
platform_device_add() only the probe callback is calling
pm_runtime_enable() which leads to an unbalanced counter.

Change-Id: I28bcd20568d93a48c760551b701a234edaec5ecc
Signed-off-by: Jack Pham <jackp@codeaurora.org>