Update FYSETC S6 Peripheral Pins (#16593)

buildroot/share/PlatformIO/variants/FYSETC_S6/PeripheralPins.c

   //  {PB_10, USART3,  STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF7_USART3)},
   //  {PC_6,  USART6,  STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF8_USART6)},
   //  {PC_10, UART4,   STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF8_UART4)},
-  {PD_2, USART3,  STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF7_USART3)},
+  {PC_10, USART3,  STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF7_USART3)},
   //  {PC_12, UART5,   STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF8_UART5)},
   {NC,    NP,    0}
 };