usb: dwc3: Free resource immediately after use

When we read an array of integers from device properties,
the temporary buffer is allocated.

However, in case of dwc3_set_incr_burst_type() it's not freed.
Free allocated buffer immediately after use.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>