usb: dwc3: Add frame length adjustment quirk

Add adjust_frame_length_quirk for writing to fladj register
which adjusts (micro)frame length to value provided by
"snps,quirk-frame-length-adjustment" property thus avoiding
USB 2.0 devices to time-out over a longer run

Signed-off-by: Nikhil Badola <nikhil.badola@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>