asdk-repo-libdce

libdce[Android]: Defer rpmsg_dce device open till buffer lock phase

In the current architecture, rpmsg_dce device is opened
during memplugin_open(), which can be called from any process
context. With Android system configured in SE Linux Enforcement
mode, it is not allowed to open rpmsg_dce in any process other than
mediaserver. Hence the device open logic is deferred till
dce buffer lock API where the actual device ioctls are needed.

Change-Id: Iedacfd3327e0ee975a8a492b057aac576d7f7c10
Signed-off-by: Sunita Nadampalli <sunitan@ti.com>