net: dsa: sja1105: Prevent leaking memory

In sja1105_static_config_upload, in two cases memory is leaked: when
static_config_buf_prepare_for_upload fails and when sja1105_inhibit_tx
fails. In both cases config_buf should be released.

Fixes: 8aa9ebcc ("net: dsa: Introduce driver for NXP SJA1105 5-port L2 switch")
Fixes: 1a4c6940 ("net: dsa: sja1105: Prevent PHY jabbering during switch reset")
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>