defconfig: lito: enable compilation of fastrpc driver

Enable compilation of the fastrpc driver, which provides a
communication mechanism that allows clients to make remote method
invocations across processor boundary to applications and compute
DSP processors.

Change-Id: I1f1881eaa81aae582c7cd7f40aef7a24311d6000
Acked-by: Vishnu Karthik D <vikarthi@qti.qualcomm.com>
Signed-off-by: Tharun Kumar Merugu <mtharu@codeaurora.org>