Bug in STM32 Disco L475 Arduino I2C header

[kartben]

Describe the bug

disco l475 board exposes I2C3 on standard Arduino Uno pins A4/A5, but the DTS file exposes I2C1 instead.

To Reproduce

Environment (please complete the following information):

• OS: all
• Toolchain (e.g Zephyr SDK, ...) 0.16.8
• Commit SHA or Version used v3.6.0

Additional context

[erwango]

PR Merged (#76497)