wifi: ath11k: use kstrtoul_from_user() where appropriate

Use 'kstrtoul_from_user()' in 'ath11k_write_file_spectral_count()'
and 'ath11k_write_file_spectral_bins()'
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230824075121.121144-4-dmantipov@yandex.ru

drivers/net/wireless/ath/ath11k/spectral.c

@@ -382,16 +382,11 @@ static ssize_t ath11k_write_file_spectral_count(struct file *file,
 {
 	struct ath11k *ar = file->private_data;
 	unsigned long val;
-	char buf[32];
-	ssize_t len;
-
-	len = min(count, sizeof(buf) - 1);
-	if (copy_from_user(buf, user_buf, len))
-		return -EFAULT;
+	ssize_t ret;
 
-	buf[len] = '\0';
-	if (kstrtoul(buf, 0, &val))
-		return -EINVAL;
+	ret = kstrtoul_from_user(user_buf, count, 0, &val);
+	if (ret)
+		return ret;
 
 	if (val > ATH11K_SPECTRAL_SCAN_COUNT_MAX)
 		return -EINVAL;
@@ -437,16 +432,11 @@ static ssize_t ath11k_write_file_spectral_bins(struct file *file,
 {
 	struct ath11k *ar = file->private_data;
 	unsigned long val;
-	char buf[32];
-	ssize_t len;
-
-	len = min(count, sizeof(buf) - 1);
-	if (copy_from_user(buf, user_buf, len))
-		return -EFAULT;
+	ssize_t ret;
 
-	buf[len] = '\0';
-	if (kstrtoul(buf, 0, &val))
-		return -EINVAL;
+	ret = kstrtoul_from_user(user_buf, count, 0, &val);
+	if (ret)
+		return ret;
 
 	if (val < ATH11K_SPECTRAL_MIN_BINS ||
 	    val > ar->ab->hw_params.spectral.max_fft_bins)