usb: dwc: using atomic kzalloc

The function dwc3_msm_ep_queue() can be called from an
interrupt context. As such, must use the GFP_ATOMIC
flag when allocating memory.

Change-Id: I2003b5e6941b5d09d1388bec9a71d04569eeda76
Signed-off-by: Dov Levenglick <dovl@codeaurora.org>