net/sched: flower: refactor control flag definitions

net/sched: flower: refactor control flag definitions

Redefine the flower control flags as an enum, so they are
included in BTF info.

Make the kernel-side enum a more explicit superset of
TCA_FLOWER_KEY_FLAGS_*, new flags still need to be added to
both enums, but at least the bit position only has to be
defined once.

FLOW_DIS_ENCAPSULATION is never set for mask, so it can't be
exposed to userspace in an unsupported flags mask error message,
so it will be placed one bit position above the last uAPI flag.

Suggested-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
Reviewed-by: Davide Caratti <dcaratti@redhat.com>
Link: https://patch.msgid.link/20240713021911.1631517-2-ast@fiberby.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>