An earlier bugfix introduced a dependency on CONFIG_NET_SCH_TAPRIO,
but this missed the case of NET_SCH_TAPRIO=m and NET_DSA_SJA1105=y,
which still causes a link error:

drivers/net/dsa/sja1105/sja1105_tas.o: In function `sja1105_setup_tc_taprio':
sja1105_tas.c:(.text+0x5c): undefined reference to `taprio_offload_free'
sja1105_tas.c:(.text+0x3b4): undefined reference to `taprio_offload_get'
drivers/net/dsa/sja1105/sja1105_tas.o: In function `sja1105_tas_teardown':
sja1105_tas.c:(.text+0x6ec): undefined reference to `taprio_offload_free'

Change the dependency to only allow selecting the TAS code when it
can link against the taprio code.

Fixes: a8d570de ("net: dsa: sja1105: Add dependency for NET_DSA_SJA1105_TAS")
Fixes: 317ab5b8 ("net: dsa: sja1105: Configure the Time-Aware Scheduler via tc-taprio offload")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>