usb: dwc3: Fix UTMI/UTMIW phy interface initialization

DWC3 support phy interfaces like 8/16-bit UTMI+. phy interface
initialization code would handle them properly along with UNKNOWN
type by default if none of the user/board doesn't need to use the
phy interfaces at all.

The current code is masking the 8/16-bit UTMI+ interface bits globally
which indeed effect the UNKNOWN cases, therefore it effects the platforms
which are not using phy interfaces at all.

So, handle the phy masking bits accordingly on respective interface
type cases.

Fixes: 6b7ebff0 ("usb: dwc3: Add phy interface for dwc3_uboot")
Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>