rpmsg: core: Clean up resources on announce_create failure.

During the rpmsg_dev_probe, if rpdev->ops->announce_create returns an
error, the rpmsg device and default endpoint should be freed before
exiting the function.

Fixes: 5e619b48 ("rpmsg: Split rpmsg core and virtio backend")
Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20211206190758.10004-1-arnaud.pouliquen@foss.st.com


Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>