soc: qcom: glink_smd_xprt: add channel lookup failure handling

If an invalid remote channel ID is received, it will not be found in the
channel list resulting in using the last channel in the list for an
operation.

Add detection and proper handling of invalid channel IDs.

Change-Id: Ib0f9107b7c2c0c2e105fd8f982f81ddeaff6d66e
Signed-off-by: Eric Holmberg <eholmber@codeaurora.org>