fm10k: remove FM10K_FLAG_DEBUG_STATS

The debug statistics were removed due to complications with the ethtool
statistics API which are not possible to resolve without a new
statistics interface. The flag was left behind, but we no longer need
it.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>