usb: xhci: annotate switch/case fallthrough properly

The USB XHCI code uses an implicit switch/case fallthrough to share code
for handling full speed and low speed transfers.

Add our "fallthrough;" statement-like macro before the second label in
the XHCI code, to avoid a warning when GCC's -Wimplicit-fallthrough
warning option is enabled.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
1 file changed