ASoC: sti: error handling bug in sti_uniperiph_cpu_dai_of()

There is a stray '!' which means the condition is never true.

Fixes: f3bd847e

 ('ASoC: sti: Add uniperipheral dai driver')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mark Brown <broonie@kernel.org>