ASoC: SOF: logger: fix errors on copy_to_user() status

copy_to_user() returns the number of bytes that could not be copied.
Testing for the return value being equal to the requested value is not
correct.

Treat a non-zero return as an error

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

Author: plbossart

sound/soc/sof/trace.c

@@ -86,7 +86,7 @@ static ssize_t sof_dfsentry_trace_read(struct file *file, char __user *buffer,
 
 	/* copy available trace data to debugfs */
 	rem = copy_to_user(buffer, dfse->buf + lpos, count);
-	if (rem == count)
+	if (rem)
 		return -EFAULT;
 
 	*ppos += count;