ALSA: echoaudio: check kmalloc() result

If kmalloc() fails exit with -ENOMEM.
Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
Ack-by: Giuliano Pochini <pochini@shiny.it>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/echoaudio/echoaudio.c

@@ -2250,6 +2250,8 @@ static int snd_echo_resume(struct pci_dev *pci)
 	DE_INIT(("resume start\n"));
 	pci_restore_state(pci);
 	commpage_bak = kmalloc(sizeof(struct echoaudio), GFP_KERNEL);
+	if (commpage_bak == NULL)
+		return -ENOMEM;
 	commpage = chip->comm_page;
 	memcpy(commpage_bak, commpage, sizeof(struct comm_page));