net/mlx5: add new flow counter Verbs API to glue library

net/mlx5: add new flow counter Verbs API to glue library

This patch updates the mlx5 glue library, new counter support
Verbs function pointers are added to the glue linking structure
mlx5_glue. This structure now contains the pointers to the both
versions of counter supporting functions due to compatibility
issues. Depending on configuration macros the functions perform
actual Verbs library calls or return an error with meaning
"feature is not supported" (NULL or ENOTSUP).

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>