Adds option to read ROTPK from registers for FVP

Enables usage of ARM_ROTPK_LOCATION=regs for FVP board.
Removes hard-coded developer keys. Instead, setting
ARM_ROTPK_LOCATION=devel_* takes keys from default directory.
In case of ROT_KEY specified - generates a new hash and replaces the
original.

Note: Juno board was tested by original feature author and was not tested
for this patch since we don't have access to the private key. Juno
implementation was moved to board-specific file without changing
functionality. It is not known whether byte-swapping is still needed
for this platform.

Change-Id: I0fdbaca0415cdcd78f3a388551c2e478c01ed986
Signed-off-by: Max Shvetsov <maksims.svecovs@arm.com>
diff --git a/plat/arm/board/fvp/fvp_trusted_boot.c b/plat/arm/board/fvp/fvp_trusted_boot.c
index dc50764..a09b80e 100644
--- a/plat/arm/board/fvp/fvp_trusted_boot.c
+++ b/plat/arm/board/fvp/fvp_trusted_boot.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,12 +9,31 @@
 #include <string.h>
 
 #include <lib/mmio.h>
-
+#include <plat/arm/common/plat_arm.h>
 #include <plat/common/platform.h>
 #include <platform_def.h>
 #include <tools_share/tbbr_oid.h>
 
 /*
+ * Return the ROTPK hash in the following ASN.1 structure in DER format:
+ *
+ * AlgorithmIdentifier  ::=  SEQUENCE  {
+ *     algorithm         OBJECT IDENTIFIER,
+ *     parameters        ANY DEFINED BY algorithm OPTIONAL
+ * }
+ *
+ * DigestInfo ::= SEQUENCE {
+ *     digestAlgorithm   AlgorithmIdentifier,
+ *     digest            OCTET STRING
+ * }
+ */
+int plat_get_rotpk_info(void *cookie, void **key_ptr, unsigned int *key_len,
+			unsigned int *flags)
+{
+	return arm_get_rotpk_info(key_ptr, key_len, flags);
+}
+
+/*
  * Store a new non-volatile counter value.
  *
  * On some FVP versions, the non-volatile counters are read-only so this