i40e: avoid duplicate private flags definitions

Separate the global private flags and the regular private flags per
interface into two arrays. Future additions of private flags will not
need to be duplicated which may lead to buggy code. Also rename
"i40e_priv_flags_strings_gl" to "i40e_gl_priv_flags_strings" for
clarity, as it reads more naturally.

Change-ID: I68caef3c9954eb7da342d7f9d20f2873186f2758
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>