rpmsg: glink: Avoid infinite loop on intent for missing channel

[ Upstream commit 3e74ec2f39362bffbd42854acbb67c7f4cb808f9 ]

In the event that an intent advertisement arrives on an unknown channel
the fifo is not advanced, resulting in the same message being handled
over and over.

Fixes: dacbb35e ("rpmsg: glink: Receive and store the remote intent buffers")
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-by: Chris Lew <quic_clew@quicinc.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230214234231.2069751-1-quic_bjorande@quicinc.com


Signed-off-by: Sasha Levin <sashal@kernel.org>