msm: rpm-smd: Fix error codes returned by msm_rpm_wait_for_ack

Fix msm_rpm_wait_for_ack API to return a -ENOMEM when a message id 0 is
passed in. The patch also reserves the message id 1 for cases when the
send message doesn't send duplicate data. This ensures that wait for ack
doesn't return a error code for this scenario.

Change-Id: I632e5d2d4e2c017d981bd5bf52d04b2422c81fc4
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>