SCP: Add test config for dual-chip RD-N1-Edge

Add RD-N1-Edge-Dual to SCP's test config. SCP code for RD-N1-Edge and
RD-N1-Edge-Dual is same, hence the dual-chip reuses
scp_config/fvp-rdn1edge file. Also, the test uses existing TF-A
config for the Busybox linux boot test on RD-N1-Edge-Dual FVP.

Change-Id: Ifb1766d48e166152bbe56839fe344d2541cec11f
1 file changed