ixgbe: Remove unused function ixgbe_is_media_cage_present

Remove the unused function ixgbe_is_media_cage_present that
generates a compiler warning.

Signed-off-by: Yogesh Bhosale yogesh.bhosale@intel.com

Reported by: markj
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D52467