USB: EHCI: Fix a bug in selecting the test mode

The controller is halted twice while putting a port in the test mode.
This bug was introduced unintentionally during 3.10 kernel upgrade.

Change-Id: I3addbdb8e71b6cc99aa98c99c15f74f6eb2a1034
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>