fix(qemu): fix register convention in BL31 for qemu

The commit with Change-Id:Ie417e054a7a4c192024a2679419e99efeded1705
updated the register convention r1/x1 values but missing necessary
changes in BL31.
As a result, a system panic observed during setup for BL32 when
TRANSFER_LIST is enabled due to unexpected arguments.
This patch is to fix this issue for qemu.

Change-Id: I42e581c5026f0f66d3b114204b4dff167a9bc6ae
Signed-off-by: Raymond Mao <raymond.mao@linaro.org>
diff --git a/plat/qemu/common/qemu_bl31_setup.c b/plat/qemu/common/qemu_bl31_setup.c
index e502e7b..a94cd57 100644
--- a/plat/qemu/common/qemu_bl31_setup.c
+++ b/plat/qemu/common/qemu_bl31_setup.c
@@ -68,6 +68,9 @@
 void bl31_early_platform_setup2(u_register_t arg0, u_register_t arg1,
 				u_register_t arg2, u_register_t arg3)
 {
+	bool is64 = false;
+	uint64_t hval;
+
 	/* Initialize the console to provide early debug support */
 	qemu_console_init();
 
@@ -92,6 +95,11 @@
 	 * They are stored in Secure RAM, in BL2's address space.
 	 */
 	while (bl_params) {
+#ifdef __aarch64__
+		if (bl_params->image_id == BL31_IMAGE_ID &&
+		    GET_RW(bl_params->ep_info->spsr) == MODE_RW_64)
+			is64 = true;
+#endif
 		if (bl_params->image_id == BL32_IMAGE_ID)
 			bl32_image_ep_info = *bl_params->ep_info;
 
@@ -113,11 +121,19 @@
 		panic();
 #endif
 
-	if (TRANSFER_LIST && arg1 == (TRANSFER_LIST_SIGNATURE |
-				      REGISTER_CONVENTION_VERSION_MASK) &&
-	    transfer_list_check_header((void *)arg3) != TL_OPS_NON) {
-		bl31_tl = (void *)arg3; /* saved TL address from BL2 */
-	}
+	if (!TRANSFER_LIST ||
+	    !transfer_list_check_header((void *)arg3))
+		return;
+
+	if (is64)
+		hval = TRANSFER_LIST_HANDOFF_X1_VALUE(REGISTER_CONVENTION_VERSION);
+	else
+		hval = TRANSFER_LIST_HANDOFF_R1_VALUE(REGISTER_CONVENTION_VERSION);
+
+	if (arg1 != hval)
+		return;
+
+	bl31_tl = (void *)arg3; /* saved TL address from BL2 */
 }
 
 #if ENABLE_RME