cnss2: Return 0 from susped/resume for driver_ops null

During usb suspend/resume call from USB SS, if driver
ops is not present cnss should return success. presently
it is returning -EINVAL if driver_ops is NULL.

Change-Id: I43a268489107bdad1945b4a842bb9ab3abe1b4ea
Signed-off-by: Rajasekaran Kalidoss <rkalidos@codeaurora.org>