coverity: mediatek mt8188 platform build

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Change-Id: I05b8fccb334628a657d9afd69f260b3645aaceb4
diff --git a/tf_config/mt8188-default b/tf_config/mt8188-default
new file mode 100644
index 0000000..631326f
--- /dev/null
+++ b/tf_config/mt8188-default
@@ -0,0 +1,3 @@
+COREBOOT=1
+CROSS_COMPILE=aarch64-none-elf-
+PLAT=mt8188