defconfig: Enable ADSP RPC driver

Configure ADSP RPC driver, which provide a communication
mechanism that allows for clients to make remote method
invocations across processor boundary to applications
DSP processor.

Change-Id: Ice7eb36b9a07af4b7e7edd74d9dd5fecb3b5f771
Acked-by: Thyagarajan Venkatanarayanan <venkatan@qti.qualcomm.com>
Signed-off-by: Tharun Kumar Merugu <mtharu@codeaurora.org>