i2c: riic: avoid potential division by zero

Value comes from DT, so it could be 0. Unlikely, but could be.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-riic.c

@@ -313,7 +313,7 @@ static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
 	 * frequency with only 62 clock ticks max (31 high, 31 low).
 	 * Aim for a duty of 60% LOW, 40% HIGH.
 	 */
-	total_ticks = DIV_ROUND_UP(rate, t->bus_freq_hz);
+	total_ticks = DIV_ROUND_UP(rate, t->bus_freq_hz ?: 1);
 
 	for (cks = 0; cks < 7; cks++) {
 		/*