It should be possible to use ping without rptun being enabled, so striped rptun_ping out of rptun and rename to rpmsg_ping.
Signed-off-by: wangyongrong <wangyongrong@xiaomi.com>
nuttx/driver/rpmsg: new folder, extract common rpmsg api in rptun.c to rpmsg.c.
rpmsg provide rpmsg_ops to each backend for specific implementation.
Signed-off-by: wangyongrong <wangyongrong@xiaomi.com>
