ixgbe: stop re-reading flash on every get_drvinfo for e610

ixgbe: stop re-reading flash on every get_drvinfo for e610

ixgbe_get_drvinfo() calls ixgbe_refresh_fw_version() on every ethtool
query for e610 adapters.  That ends up in ixgbe_discover_flash_size(),
which bisects the full 16 MB NVM space issuing one ACI command per
step (~20 ms each, ~24 steps total = ~500 ms).

Profiling on an idle E610-XAT2 system with telegraf scraping ethtool
stats every 10 seconds:

  kretprobe:ixgbe_get_drvinfo took 527603 us
  kretprobe:ixgbe_get_drvinfo took 523978 us
  kretprobe:ixgbe_get_drvinfo took 552975 us
  kretprobe:ice_get_drvinfo   took       3 us
  kretprobe:igb_get_drvinfo   took       2 us
  kretprobe:i40e_get_drvinfo  took       5 us

The half-second stall happens under the RTNL lock, causing visible
latency on ip-link and friends.

The FW version can only change after an EMPR reset.  All flash data is
already populated at probe time and the cached adapter->eeprom_id is
what get_drvinfo should be returning.  The only place that needs to
trigger a re-read is ixgbe_devlink_reload_empr_finish(), right after
the EMPR completes and new firmware is running.  Additionally, refresh
the FW version in ixgbe_reinit_locked() so that any PF that undergoes a
reinit after an EMPR (e.g. triggered by another PF's devlink reload)
also picks up the new version in adapter->eeprom_id.

ixgbe_devlink_info_get() keeps its refresh call for explicit
"devlink dev info" queries, which is fine given those are user-initiated.

Fixes: c9e563cae19e ("ixgbe: add support for devlink reload")
Co-developed-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Rinitha S <sx.rinitha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>