mmcsd_sdio:Insure a error exiting via mmcsd_removed will not Hang system.

mmcsd_removed will be called if the card is in invalid state.
   This can happen if the card is bad, or vibrations causes a power
   loss.

   mmcsd_removed resets:
     priv->capacity     = 0; /* Capacity=0 sometimes means no media */
     priv->blocksize    = 0;
     priv->probed       = false;
     priv->mediachanged = false;
     priv->wrbusy       = false;
     priv->type         = MMCSD_CARDTYPE_UNKNOWN;
     priv->rca          = 0;
     priv->selblocklen  = 0;
     priv->widebus      = false;

  If blocksize is set to 0 will cause the log2 to result
  in an infinate loop in some drivers.

  IS_EMPTY will check for priv->type = MMCSD_CARDTYPE_UNKNOWN
  and return ENODEV.

drivers/mmcsd/mmcsd_sdio.c

@@ -1190,7 +1190,7 @@ static int mmcsd_transferready(FAR struct mmcsd_state_s *priv)
 
   /* First, check if the card has been removed. */
 
-  if (!SDIO_PRESENT(priv->dev))
+  if (IS_EMPTY(priv) || !SDIO_PRESENT(priv->dev))
     {
       ferr("ERROR: Card has been removed\n");
       return -ENODEV;