ASoC: uniphier: remove redundant check of blk_id

The check of blk_id == AUD_CLK_IO is redundant as it also being performed
in the following switch statement with the same return of -ENOTSUPP. Fix
this by removing the redundant comparison.

Detected by CoverityScan, CID#1465227 ("Logically dead code")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Mark Brown <broonie@kernel.org>