arm_fpga: Add support for unknown MPIDs

This patch allows the system to fallback to a default CPU library
in case the MPID does not match with any of the supported ones.

This feature can be enabled by setting SUPPORT_UNKNOWN_MPID build
option to 1 (enabled by default only on arm_fpga platform).

This feature can be very dangerous on a production image and
therefore it MUST be disabled for Release images.

Signed-off-by: Javier Almansa Sobrino <javier.almansasobrino@arm.com>
Change-Id: I0df7ef2b012d7d60a4fd5de44dea1fbbb46881ba
diff --git a/bl31/bl31.mk b/bl31/bl31.mk
index 735d1fc..cd6549b 100644
--- a/bl31/bl31.mk
+++ b/bl31/bl31.mk
@@ -7,6 +7,12 @@
 ################################################################################
 # Include Makefile for the SPM-MM implementation
 ################################################################################
+ifeq (${SUPPORT_UNKNOWN_MPID},1)
+  ifeq (${DEBUG},0)
+    $(warning WARNING: SUPPORT_UNKNOWN_MPID enabled)
+  endif
+endif
+
 ifeq (${SPM_MM},1)
   ifeq (${EL3_EXCEPTION_HANDLING},0)
     $(error EL3_EXCEPTION_HANDLING must be 1 for SPM-MM support)