ASoC: SOF: core: fix undefined nocodec reference

The existing code mistakenly uses IS_ENABLED in C code instead of as
in conditional compilation, leading to the following error:

ld: sound/soc/sof/core.o: in function `sof_machine_check':
sound/soc/sof/core.c:279: undefined reference to `sof_nocodec_setup'

Fix by using #if !IS_ENABLED()

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>