boards: st: stm32mp257f_ev1_stm32mp257fxx_m33.yaml: update documentation

The I2C is now supported.

Signed-off-by: Tanguy Raufflet <tanguy.raufflet@savoirfairelinux.com>

Author: Tanguy Raufflet

boards/st/stm32mp257f_ev1/stm32mp257f_ev1_stm32mp257fxx_m33.yaml

@@ -9,6 +9,7 @@ supported:
   - LED
   - gpio
   - shell
+  - i2c
 testing:
   ignore_tags:
     - cmsis_rtos_v2