Add SPDX identifiers to files under stm32 directory
Signed-off-by: NBenjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: NPhilippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>