crypto: cavium/nitrox - Fix an error rhandling path in 'nitrox_probe()'

If an error occurs after a successful 'ioremap()' call, it must be undone
by a corresponding 'iounmap()' call, as already done in the remove
function.
Add a 'pf_sw_fail' label in the error handling path and add the missing
'iounmap()'.

While at it, also add a 'flr_fail' label in the error handling path and use
it to avoid some code duplication.

Fixes: 14fa93cd ("crypto: cavium - Add support for CNN55XX adapters.")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>