ASoC: SOF: remove redundant null checks of dai

Currently there are two null checks of pointer dai in function
sof_connect_dai_widget and yet there is no null check of dai
at the end of the function when checking !dai->name.  The latter
would be a null pointer deference if dai is null (as picked up
by static analysis), however the function is only ever called
when dai is successfully allocated, so the null checks are
redundant. Clean up the code by removing the null checks.

Addresses-Coverity: ("Dereference after null check")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Mark Brown <broonie@kernel.org>