Juno: Disable SPIDEN in release builds

On Juno, the secure privileged invasive debug authentication signal
(SPIDEN) is controlled by board SCC registers, which by default enable
SPIDEN.  Disable secure privileged external debug in release builds by
programming the appropriate Juno SoC registers.

Change-Id: I61045f09a47dc647bbe95e1b7a60e768f5499f49
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
diff --git a/include/plat/arm/css/common/css_def.h b/include/plat/arm/css/common/css_def.h
index a2fe0d5..7cfaf59 100644
--- a/include/plat/arm/css/common/css_def.h
+++ b/include/plat/arm/css/common/css_def.h
@@ -101,6 +101,13 @@
 #define SSC_VERSION_DESIGNER_ID_MASK		0xff
 #define SSC_VERSION_PART_NUM_MASK		0xfff
 
+/* SSC debug configuration registers */
+#define SSC_DBGCFG_SET		0x14
+#define SSC_DBGCFG_CLR		0x18
+
+#define SPIDEN_INT_CLR_SHIFT	6
+#define SPIDEN_SEL_SET_SHIFT	7
+
 #ifndef __ASSEMBLY__
 
 /* SSC_VERSION related accessors */