rpmsg: Guard against null endpoint ops in destroy

In RPMSG GLINK the chrdev device will allocate an ept as part of the
rpdev creation. This device will not register endpoint ops even though
it has an allocated ept. Protect against the case where the device is
being destroyed.
Signed-off-by: NChris Lew <clew@codeaurora.org>
Signed-off-by: NArun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: NDeepak Kumar Singh <deesin@codeaurora.org>
Link: https://lore.kernel.org/r/1593017121-7953-3-git-send-email-deesin@codeaurora.orgSigned-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

drivers/rpmsg/rpmsg_core.c

@@ -81,7 +81,7 @@ EXPORT_SYMBOL(rpmsg_create_ept);
  */
 void rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
 {
-	if (ept)
+	if (ept && ept->ops)
 		ept->ops->destroy_ept(ept);
 }
 EXPORT_SYMBOL(rpmsg_destroy_ept);