soundwire: cadence: remove useless variable incrementation

Fix cppcheck warning:

drivers/soundwire/cadence_master.c:992:9: style: Variable 'offset' is
assigned a value that is never used. [unreadVariable]
 offset += stream->num_out;
        ^
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200113211025.27973-3-pierre-louis.bossart@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/cadence_master.c

@@ -989,8 +989,6 @@ int sdw_cdns_pdi_init(struct sdw_cdns *cdns,
 	ret = cdns_allocate_pdi(cdns, &stream->out,
 				stream->num_out, offset);
 
-	offset += stream->num_out;
-
 	if (ret)
 		return ret;