Configure synci generation explicitly

The default for synci generation is compiler version dependent

Change-Id: I3f94cabd98c45aaa4e5149e8bb050dc47efa61ca
diff --git a/core/clang/mips.mk b/core/clang/mips.mk
index 08daf40..aeb2f6a 100644
--- a/core/clang/mips.mk
+++ b/core/clang/mips.mk
@@ -12,6 +12,7 @@
   -frerun-cse-after-loop \
   -frename-registers \
   -msynci \
+  -mno-synci \
   -mno-fused-madd
 
 # We don't have any mips flags to substitute yet.