ARM: dts: stm32: move can3 node from stm32f746 to stm32f769

ARM: dts: stm32: move can3 node from stm32f746 to stm32f769

According to documents [1], [2] and [3], we have 2 CAN devices on the
stm32f746 platform and 3 on the stm32f769 platform. So let's move the
can3 node from stm32f746.dtsi to stm32f769.dtsi.

[1] https://www.st.com/en/microcontrollers-microprocessors/stm32f7-series.html
[2] RM0385: STM32F75xxx and STM32F74xxx advanced Arm®-based 32-bit MCUs
[3] RM0410: STM32F76xxx and STM32F77xxx advanced Arm®-based 32-bit MCUs
Fixes: df362914eead ("ARM: dts: stm32: re-add CAN support on stm32f746")
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>