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/include/plat/arm/common/arm_def.h b/include/plat/arm/common/arm_def.h
index 5bd53f3..c825bf4 100644
--- a/include/plat/arm/common/arm_def.h
+++ b/include/plat/arm/common/arm_def.h
@@ -18,6 +18,12 @@
  * Definitions common to all ARM standard platforms
  *****************************************************************************/
 
+/*
+ * Root of trust key hash lengths
+ */
+#define ARM_ROTPK_HEADER_LEN		19
+#define ARM_ROTPK_HASH_LEN		32
+
 /* Special value used to verify platform parameters from BL2 to BL31 */
 #define ARM_BL31_PLAT_PARAM_VAL		ULL(0x0f1e2d3c4b5a6978)