The STM32U0xx devices support only SWD. Add swd transport in the target file. Remove swd transport from the associated board files. Change-Id: I2d31856951d15fcf2d1986ee5b1b31464e68db1c Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com> Reviewed-on: https://review.openocd.org/c/openocd/+/9427 Reviewed-by: Tomas Vanek <vanekt@fbl.cz> Tested-by: jenkins Reviewed-by: Ahmed Haoues <ahmed.haoues@st.com>