radio: iris: Fix the issue with disable command

Disable command not able to send to the controller as the SMD
channel closing immediately after sending the cmd.
Add sleep after sending the disable cmd which can allow the cmd to
receive at controller and get the response back to host.

Change-Id: I7c30816dc0852b5c817142f733a4ae984881e752
CRs-Fixed: 903994
Signed-off-by: Venkateshwarlu Domakonda <vdomak@codeaurora.org>