boards: st: stm32n6: Add the usbd test feature

Add the usbd test feature to twister.yaml for the boards
nucleo_n657x0_q and stm32n6570_dk.

Signed-off-by: IBEN EL HADJ MESSAOUD Marwa <marwa.ibenelhadjmessaoud-ext@st.com>
2 files changed