net/sched: flower: define new tunnel flags

Define new TCA_FLOWER_KEY_FLAGS_* flags for use in struct
flow_dissector_key_control, covering the same flags as
currently exposed through TCA_FLOWER_KEY_ENC_FLAGS.

Put the new flags under FLOW_DIS_F_*. The idea is that we can
later, move the existing flags under FLOW_DIS_F_* as well.

The ynl flag names have been taken from the RFC iproute2 patch.

Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20240713021911.1631517-4-ast@fiberby.net


Signed-off-by: Jakub Kicinski <kuba@kernel.org>