usb: dwc3: Fix spelling of 'optimizations'

'optimizations' was misspelled as 'optmizations'. Fixed it. It is a
coding style change which should have no impact on runtime execution of code.

Signed-off-by: Faisal Mehmood <f.m3hm00d@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>