cxgb4: Update firmware version after flashing it via ethtool

After successfully loading new firmware, reload the new firmware's version
number information so "ethtool -i", etc. will report the right value

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>