[FIX] Do not try to gather information about the SFP when there's no SFP inserted.
The mlx5 kernel driver (and possibly others) emit an error when you try to run ethtool -m <interface> on an interface that does not have an SFP inserted. We therefore newly detect when there's no SFP and do not try to gather the SFP information in this case.
Feb 24 15:10:02 test.hostname kernel: mlx5_core 0000:19:00.1: mlx5_query_mcia:381:(pid 1997759): query_mcia_reg failed: status: 0x3
Feb 24 15:10:02 test.hostname kernel: mlx5_core 0000:19:00.1 eth0: mlx5e_get_module_eeprom_by_page: mlx5_query_module_eeprom_by_page failed:0xfffffffb