usb: dwc2: Fix probe problem on bcm2835

Fixes an issue found on Raspberry PI platform that prevents probe. Don't
skip setting the force mode if it's already set.

Fixes: 09c96980 ("usb: dwc2: Add functions to set and clear force mode")
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Reported-by: Stefan Wahren <stefan.wahren@i2se.com>
Reported-by: Remi Pommarel <repk@triplefau.lt>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Remi Pommarel <repk@triplefau.lt>
Signed-off-by: Felipe Balbi <balbi@kernel.org>