net/mlxfw: Improve FSM err message reporting and return codes

Report unique and standard error codes corresponding to the specific
FW flash error. In addition, add a more detailed error messages to
netlink.

Before:
$ devlink dev flash pci/0000:05:00.0 file ...
Error: mlxfw: Firmware flash failed.
devlink answers: Invalid argument

After:
$ devlink dev flash pci/0000:05:00.0 file ...
Error: mlxfw: Firmware flash failed: pending reset.
devlink answers: Device busy

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>