ALSA: compress_offload: remove redundant initialization

Fix cppcheck warning:

sound/core/compress_offload.c:1044:6: style: Redundant initialization
for 'ret'. The initialized value is overwritten before it is
read. [redundantInitialization]

 ret = snd_register_device(SNDRV_DEVICE_TYPE_COMPRESS,
     ^
sound/core/compress_offload.c:1034:10: note: ret is initialized
 int ret = -EINVAL;
         ^
sound/core/compress_offload.c:1044:6: note: ret is overwritten
 ret = snd_register_device(SNDRV_DEVICE_TYPE_COMPRESS,
     ^

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Acked-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20200902212133.30964-8-pierre-louis.bossart@linux.intel.com


Signed-off-by: Takashi Iwai <tiwai@suse.de>