usb: dwc3-msm: Fix out-of-bounds access in bus voting

The for loop in dwc3_msm_update_bus_bw() was using a NULL
condition rather than against ARRAY_SIZE(mdwc->icc_paths).
This can result in an out-of-bounds access if the memory
just beyond the array also happens to be non-zero.

Change-Id: Ib1f003f774b125a156ceb0070cd9d98a4d1f03ee
Signed-off-by: Jack Pham <jackp@codeaurora.org>