idpf: convert vport state to bitmap

idpf: convert vport state to bitmap

Convert vport state to a bitmap and remove the DOWN state which is
redundant in the existing logic. There are no functional changes aside
from the use of bitwise operations when setting and checking the states.
Removed the double underscore to be consistent with the naming of other
bitmaps in the header and renamed current_state to vport_is_up to match
the meaning of the new variable.

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Chittim Madhu <madhu.chittim@intel.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Samuel Salin <Samuel.salin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://patch.msgid.link/20251125223632.1857532-6-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>