ALSA: hda: take reg_lock in azx_init_cmd_io/azx_free_cmd_io

Just for safety.  azx_init_cmd_io() and azx_free_cmd_io() may be
called when switching to single command mode.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_intel.c

@@ -513,6 +513,7 @@ static int azx_alloc_cmd_io(struct azx *chip)
 
 static void azx_init_cmd_io(struct azx *chip)
 {
+	spin_lock_irq(&chip->reg_lock);
 	/* CORB set up */
 	chip->corb.addr = chip->rb.addr;
 	chip->corb.buf = (u32 *)chip->rb.area;
@@ -544,13 +545,16 @@ static void azx_init_cmd_io(struct azx *chip)
 	azx_writew(chip, RINTCNT, 1);
 	/* enable rirb dma and response irq */
 	azx_writeb(chip, RIRBCTL, ICH6_RBCTL_DMA_EN | ICH6_RBCTL_IRQ_EN);
+	spin_unlock_irq(&chip->reg_lock);
 }
 
 static void azx_free_cmd_io(struct azx *chip)
 {
+	spin_lock_irq(&chip->reg_lock);
 	/* disable ringbuffer DMAs */
 	azx_writeb(chip, RIRBCTL, 0);
 	azx_writeb(chip, CORBCTL, 0);
+	spin_unlock_irq(&chip->reg_lock);
 }
 
 static unsigned int azx_command_addr(u32 cmd)