usb: ehci-msm2: Fix unbalanced clock warning

The EHCI controller may be in suspend state in which its clocks
are already disabled. Fix warning given by clock subsystem when
disabling the clocks a second time when the controller's platform
device is removed by first checking if the device is suspended.

Change-Id: I3c491d0db11cc172d0e6779042c04fc726936b36
Signed-off-by: Jack Pham <jackp@codeaurora.org>