defconfig: Disable SMP2P tests

The smp2p unit tests do not add any deliverable functionality.
Disable the tests before removing them from the kernel.

CRs-Fixed: 2120485
Change-Id: I30e8e238ba29653fad750193989539b1a7f77f45
Signed-off-by: Chris Lew <clew@codeaurora.org>