hikey: Add development TBB support

This patch adds experimental support for TRUSTED_BOARD_BOOT to the
Hikey. This is adapted from the RPi3 and QEMU implementations.

Since the Hikey starts from BL2 the TRUSTED_BOARD_BOOT ROT begins there
too. When TRUSTED_BOARD_BOOT is defined, the BL1 build is skipped.

See the following example:

make \
 PLAT=hikey \
 BL33=u-boot.bin \
 SCP_BL2=mcuimage.bin \
 TRUSTED_BOARD_BOOT=1 \
 MBEDTLS_DIR=../../mbedtls \
 GENERATE_COT=1 \
 all fip

Signed-off-by: Teddy Reed <teddy.reed@gmail.com>
diff --git a/plat/hisilicon/hikey/include/hikey_layout.h b/plat/hisilicon/hikey/include/hikey_layout.h
index 637a1c9..5c593fc 100644
--- a/plat/hisilicon/hikey/include/hikey_layout.h
+++ b/plat/hisilicon/hikey/include/hikey_layout.h
@@ -58,10 +58,10 @@
  * + loader +
  * ++++++++++ 0xF980_1000
  * +  BL2   +
- * ++++++++++ 0xF981_8000
+ * ++++++++++ 0xF983_0000
  */
 #define BL2_BASE			(BL1_RO_BASE)		/* 0xf980_1000 */
-#define BL2_LIMIT			(0xF9818000)		/* 0xf981_8000 */
+#define BL2_LIMIT			(0xF9830000)		/* 0xf983_0000 */
 
 /*
  * SCP_BL2 specific defines.