idpf: remove obsolete stashing code

With the new Tx buffer management scheme, there is no need for all of
the stashing mechanisms, the hash table, the reserve buffer stack, etc.
Remove all of that.

Signed-off-by: Joshua Hay <[email protected]>
Reviewed-by: Madhu Chittim <[email protected]>
Reviewed-by: Aleksandr Loktionov <[email protected]>
Tested-by: Samuel Salin <[email protected]>
Signed-off-by: Tony Nguyen <[email protected]>

Author: jahay1