usb: bam: fix race condition between usb bam and controller

When waking up with the USB cable disconnected, the DWC3 driver
invokes its set_suspend function, which calls
msm_bam_device_lpm_ok. If the usb_bam_probe function hasn't
finished, this results an an attempt to call spin_lock on an
uninitialized lock.
Adding an automatic successful return from msm_bam_device_lpm_ok
if the probe hasn't finished, since this function should return 0
whenever the bam is not a blocking factor to the suspend flow.

Change-Id: Ief52bf12877124281dfd41d5639e72da8055ee5b
Signed-off-by: Dov Levenglick <dovl@codeaurora.org>