libertas: fix spinlock recursion bug

This fixes a bug detected by CONFIG_DEBUG_SPINLOCK:

if_cs_get_int_status() is only called from lbs_thread(), via
priv->hw_get_int_status. However, lbs_thread() has already taken the
priv->driver_lock. So it's a fault to take the same lock again here.
Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/libertas/if_cs.c

@@ -677,9 +677,7 @@ sbi_get_int_status_exit:
 
 	/* Card has a command result for us */
 	if (*ireg & IF_CS_C_S_CMD_UPLD_RDY) {
-		spin_lock(&priv->driver_lock);
 		ret = if_cs_receive_cmdres(priv, priv->upld_buf, &priv->upld_len);
-		spin_unlock(&priv->driver_lock);
 		if (ret < 0)
 			lbs_pr_err("could not receive cmd from card\n");
 	}