fm10k: remove debug-statistics support

This change fixes an (ab)use of the ethtool stats API, which could
result in corrupt memory or misleading stat output. The ethtool stats
API is not robust enough to handle varying number of statistics due to
how it requests the size and allocates memory. Remove the poorly conceived
support originally added for extra debug statistics. In the future,
a new stats API may open up the ability to display these statistics.

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>