net: dsa: felix: build as module when tc-taprio is module

net: dsa: felix: build as module when tc-taprio is module

felix_vsc9959.c calls taprio_offload_get() and taprio_offload_free(),
symbols exported by net/sched/sch_taprio.c. As such, we must disallow
building the Felix driver as built-in when the symbol exported by
tc-taprio isn't present in the kernel image.

Fixes: 1c9017e44af2 ("net: dsa: felix: keep reference on entire tc-taprio config")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20220704190241.1288847-2-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>