ASoC: AMD: Fix build warning

Fixes
sound/soc/amd/acp-da7219-max98357a.c: In function 'cz_probe':
sound/soc/amd/acp-da7219-max98357a.c:367:3: warning: 'ret' may
be used uninitialized in this function [-Wmaybe-uninitialized]
   dev_err(&pdev->dev, "Failed to register regulator: %d\n",
ret);

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Akshu Agrawal <akshu.agrawal@amd.com>
Signed-off-by: Mark Brown <broonie@kernel.org>