dsp: afe: get apr handle before sending apr pkt

Make sure to get apr handle before sending a packet
so that it does not end up with no handle to send
the apr packet.

Change-Id: Iaaebee3ddc6c83896e4cb9dc8149d310fc7d67f1
Signed-off-by: Karthikeyan Mani <kmani@codeaurora.org>