In case we fail to ioremap() one of our registers, we would be leaking
existing mappings, unwind those accordingly on errors.
Fixes: 246d7f773c13 ("net: dsa: add Broadcom SF2 switch driver")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>