iio: chemical: sps30: fix a loop timeout test

The "while (tries--) {" loop is a postop so it exits with "tries" set
to -1.

Fixes: 232e0f6d ("iio: chemical: add support for Sensirion SPS30 sensor")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/chemical/sps30.c

@@ -210,7 +210,7 @@ static int sps30_do_meas(struct sps30_state *state, s32 *data, int size)
 		msleep_interruptible(300);
 	}
 
-	if (!tries)
+	if (tries == -1)
 		return -ETIMEDOUT;
 
 	ret = sps30_do_cmd(state, SPS30_READ_DATA, tmp, sizeof(int) * size);