sfc: use flow_rule_is_supp_enc_control_flags()

Change the existing check for unsupported encapsulation control flags,
to use the new helper flow_rule_is_supp_enc_control_flags().

No functional change, only compile tested.

Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Davide Caratti <dcaratti@redhat.com>
Link: https://lore.kernel.org/r/20240609173358.193178-3-ast@fiberby.net


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