drivers: serial: ra8_sci_b: revise switch-case in callback_adapter

Unified switch-case usage in `uart_ra_sci_b_callback_adapter` to use
`break` instead of `return`.
Typically, a `break` is used in switch-case statements unless an early
return is necessary, in which case `return` is appropriate.

For this case, using a `break` statement is the more suitable choice.

Signed-off-by: Pisit Sawangvonganan <[email protected]>

Author: ndrs-pst

drivers/serial/uart_renesas_ra8_sci_b.c

@@ -803,24 +803,28 @@ static void uart_ra_sci_b_callback_adapter(struct st_uart_callback_arg *fsp_args
 	case UART_EVENT_TX_COMPLETE: {
 		data->tx_buffer_len = data->tx_buffer_cap;
 		async_update_tx_buffer(dev);
-		return;
+		break;
 	}
 	case UART_EVENT_RX_COMPLETE: {
 		data->rx_buffer_len =
 			data->rx_buffer_cap - data->rx_buffer_offset - data->sci.rx_dest_bytes;
 		async_rx_ready(dev);
 		async_release_rx_buffer(dev);
 		async_replace_rx_buffer(dev);
-		return;
+		break;
 	}
 	case UART_EVENT_ERR_PARITY:
-		return async_rx_error(dev, UART_ERROR_PARITY);
+		async_rx_error(dev, UART_ERROR_PARITY);
+		break;
 	case UART_EVENT_ERR_FRAMING:
-		return async_rx_error(dev, UART_ERROR_FRAMING);
+		async_rx_error(dev, UART_ERROR_FRAMING);
+		break;
 	case UART_EVENT_ERR_OVERFLOW:
-		return async_rx_error(dev, UART_ERROR_OVERRUN);
+		async_rx_error(dev, UART_ERROR_OVERRUN);
+		break;
 	case UART_EVENT_BREAK_DETECT:
-		return async_rx_error(dev, UART_BREAK);
+		async_rx_error(dev, UART_BREAK);
+		break;
 	case UART_EVENT_TX_DATA_EMPTY:
 	case UART_EVENT_RX_CHAR:
 		break;