soc: qcom: glink_pkt: Add intent ioctl handling

Add support for the previously supported ioctl to queue an rx intent.
RPMSG queues intents for clients automatically, the ioctl to queue
them is no longer needed. Return success so userspace client logic
is not broken.

Change-Id: I74407c10f8163944575fd9fc33386cfbce98d08b
Signed-off-by: Chris Lew <clew@codeaurora.org>