ARM: dts: stm32: lxa-mc1: add OSD32MP15x to list of compatibles

Earlier commit modified the binding, so the SiP is to be specified
as well. Adjust the device tree accordingly.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>