firewire: core: fw_device_refresh(): clean up error handling

In fw_device_init() and fw_device_refresh(), if a call to
read_cofig_rom() fails, the operation is retried a few times, with
these retries being controlled by the MAX_RETRIES and RETRY_DELAY
symbols.

fw_device_refresh() also reads part of the config rom by calling
reread_config_rom().  Any errors from this call resulted in retries
with MAX_RETRIES/2 and RETRY_DELAY/2.

There is no reason to require that a device that has initiated a bus
reset must react faster to read requests than a device that has just
been plugged in.  Furthermore, if the config rom has changed, any
errors from the following read_config_rom() call are then handled
with the normal retry count and delay.

Remove this inconsistency by always using the normal retry count and
delay.  (This also makes the two error handlers identical and allows
merging them.)

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>