i40e: split function for hash and flow director input

i40e: split function for hash and flow director input

For the input set selection, Hash filter and Flow director shared
the same function, i.e. i40e_filter_inset_select.
For code readability, this patch replaces i40e_filter_inset_select
with two new functions: i40e_hash_filter_inset_select and
i40e_fdir_filter_inset_select for Hash filter and Flow director
respectively.

Signed-off-by: Jingjing Wu <jingjing.wu@intel.com>
Acked-by: Helin Zhang <helin.zhang@intel.com>