ath10k: spectral: remove redundant check in write_file_spectral_count()

Variable val is unsigned, so checking whether it is less than zero is
redundant.

Signed-off-by: Christos Gkekas <chris.gekas@gmail.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/spectral.c

@@ -406,7 +406,7 @@ static ssize_t write_file_spectral_count(struct file *file,
 	if (kstrtoul(buf, 0, &val))
 		return -EINVAL;
 
-	if (val < 0 || val > 255)
+	if (val > 255)
 		return -EINVAL;
 
 	mutex_lock(&ar->conf_mutex);