drivers: hv: Fix missing error code in vmbus_connect()

Eliminate the follow smatch warning:

drivers/hv/connection.c:236 vmbus_connect() warn: missing error code
'ret'.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1621940321-72353-1-git-send-email-jiapeng.chong@linux.alibaba.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>