i2c: digicolor: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1].

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

---
Changes in v2:
- Update URL. Use proper URL to Linux v5.7 documentation.

 drivers/i2c/busses/i2c-digicolor.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 332f00437479..f67639dc74b7 100644
@@ -187,7 +187,7 @@ static irqreturn_t dc_i2c_irq(int irq, void *dev_id)
 			break;
 		}
 		i2c->state = STATE_WRITE;
-		/* fall through */
+		fallthrough;
 	case STATE_WRITE:
 		if (i2c->msgbuf_ptr < i2c->msg->len)
 			dc_i2c_write_buf(i2c);

2.27.0