phy: rockchip-inno-usb2: don't cancel otg_sm_work when phy exit

phy: rockchip-inno-usb2: don't cancel otg_sm_work when phy exit

The otg_sm_work is a OTG state machine delay work. It will hold
a wake lock if SDP cable or CDP cable is attached, and release
the wake lock if cable dettached. If usb controller(e.g. DWC3)
call phy exit When USB cable is dettached and cancel otg_sm_work,
it will cause the usb phy keeping hold of wake lock.

Change-Id: Ie6a89e481b8d4999a996083709bacc5be901805a
Signed-off-by: Wu Liang feng <wulf@rock-chips.com>