rpmsg: qcom_smd: Fix uninitialized return variable in __qcom_smd_send()

The "ret" variable isn't initialized if we don't enter the loop.  For
example,  if "channel->state" is not SMD_CHANNEL_OPENED.

Fixes: 33e3820 ("rpmsg: smd: Use spinlock in tx path")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/aAkhvV0nSbrsef1P@stanley.mountain
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

Author: Dan Carpenter

drivers/rpmsg/qcom_smd.c

@@ -746,7 +746,7 @@ static int __qcom_smd_send(struct qcom_smd_channel *channel, const void *data,
 	__le32 hdr[5] = { cpu_to_le32(len), };
 	int tlen = sizeof(hdr) + len;
 	unsigned long flags;
-	int ret;
+	int ret = 0;
 
 	/* Word aligned channels only accept word size aligned data */
 	if (channel->info_word && len % 4)