[ALSA] echoaudio - Add barrier() to prevent compiler optimization

This patch adds a barrier() to prevent the compiler from
moving the read outside of the loop. It also fixes a comment.
Signed-off-by: NGiuliano Pochini <pochini@shiny.it>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@suse.cz>

sound/pci/echoaudio/echoaudio_dsp.c

@@ -43,11 +43,11 @@ static int wait_handshake(struct echoaudio *chip)
 {
 	int i;
 
-	/* Wait up to 10ms for the handshake from the DSP */
+	/* Wait up to 20ms for the handshake from the DSP */
 	for (i = 0; i < HANDSHAKE_TIMEOUT; i++) {
 		/* Look for the handshake value */
+		barrier();
 		if (chip->comm_page->handshake) {
-			/*if (i)  DE_ACT(("Handshake time: %d\n", i));*/
 			return 0;
 		}
 		udelay(1);