msm: rpm-smd: Send notifications during send_data

Send sleep notifications when the driver is ready to send the data
instead of when a KVP is being added. The driver could potentially
update a KVP multiple times before sending the data out. This also
prevents the notifiers from getting called recursively by the low power
management driver.

Change-Id: I6e2b8009279f75132d4213db6bef55682cc5e23d
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>