arm64: defconfig: enable CONFIG_FSL_ENETC_QOS

Now that we have the needed network scheduler, we can enable the ENETC
hardware support.

$ scripts/bloat-o-meter old-vmlinux vmlinux
add/remove: 19/2 grow/shrink: 12/0 up/down: 12852/-16 (12836)
[..]
Total: Before=20428273, After=20441109, chg +0.06%

Link: https://lore.kernel.org/r/20200707223114.16355-2-michael@walle.cc


Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>