cassini: Fix a memory leak in the error handling path of cas_init_one()

cas_saturn_firmware_init() allocates some memory using vmalloc(). This
memory is freed in the .remove() function but not it the error handling
path of the probe.

Add the missing vfree() to avoid a memory leak, should an error occur.

Fixes: fcaa40669c ("cassini: use request_firmware")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sun/cassini.c

@@ -5077,6 +5077,8 @@ err_out_iounmap:
 		cas_shutdown(cp);
 	mutex_unlock(&cp->pm_mutex);
 
+	vfree(cp->fw_data);
+
 	pci_iounmap(pdev, cp->regs);