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/hikey_rotpk.S b/plat/hisilicon/hikey/hikey_rotpk.S
new file mode 100644
index 0000000..f308eee
--- /dev/null
+++ b/plat/hisilicon/hikey/hikey_rotpk.S
@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+	.global hikey_rotpk_hash
+	.global hikey_rotpk_hash_end
+	.section .rodata.hikey_rotpk_hash, "a"
+hikey_rotpk_hash:
+	/* DER header */
+	.byte 0x30, 0x31, 0x30, 0x0D, 0x06, 0x09, 0x60, 0x86, 0x48
+	.byte 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20
+	/* SHA256 */
+	.incbin ROTPK_HASH
+hikey_rotpk_hash_end: