ASoC: ingenic: Unconditionally depend on devicetree

ASoC: ingenic: Unconditionally depend on devicetree

All boards with Ingenic SoCs probe with devicetree already, we have no
use for a non-devicetree path.

This solves some compilation warnings that were caused by unused
variables in the case where CONFIG_OF was disabled.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20200523125455.12392-1-paul@crapouillou.net
Signed-off-by: Mark Brown <broonie@kernel.org>