ARM: dts: stm32: add an extra pin map for USART1 on stm32h743

ARM: dts: stm32: add an extra pin map for USART1 on stm32h743

Add an additional pin map configuration for using the USART1 controller
on the stm32h743 MCU.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/r/20250427074404.3278732-8-dario.binacchi@amarulasolutions.com
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
[ upstream commit: 8e71dfe46a4a1e9505b1a327470f879b63388968 ]

(cherry picked from commit 9d5ec2c9c5d5131e701447c5c32aaf6c688c6e01)