plat/arm/board/fvp: Add support for Measured Boot

This patch adds support for Measured Boot functionality
to FVP platform code. It also defines new properties
in 'tpm_event_log' node to store Event Log address and
it size
'tpm_event_log_sm_addr'
'tpm_event_log_addr'
'tpm_event_log_size'
in 'event_log.dtsi' included in 'fvp_tsp_fw_config.dts'
and 'fvp_nt_fw_config.dts'. The node and its properties
are described in binding document
'docs\components\measured_boot\event_log.rst'.

Change-Id: I087e1423afcb269d6cfe79c1af9c348931991292
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
diff --git a/docs/components/measured_boot/event_log.rst b/docs/components/measured_boot/event_log.rst
new file mode 100644
index 0000000..5347dcc
--- /dev/null
+++ b/docs/components/measured_boot/event_log.rst
@@ -0,0 +1,35 @@
+DTB binding for Event Log properties
+====================================
+
+This document describes the device tree format of Event Log properties.
+These properties are not related to a specific platform and can be queried
+from common code.
+
+Dynamic configuration for Event Log
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Measured Boot driver expects a *tpm_event_log* node with the following field
+in 'nt_fw_config' and 'tsp_fw_config' DTS files:
+
+- compatible [mandatory]
+   - value type: <string>
+   - Must be the string "arm,tpm_event_log".
+
+Then a list of properties representing Event Log configuration, which
+can be used by Measured Boot driver. Each property is named according
+to the information it contains:
+
+- tpm_event_log_sm_addr [fvp_nt_fw_config.dts with OP-TEE]
+    - value type: <u64>
+    - Event Log base address in secure memory.
+
+Note. Currently OP-TEE does not support reading DTBs from Secure memory
+and this property should be removed when this feature is supported.
+
+- tpm_event_log_addr [mandatory]
+    - value type: <u64>
+    - Event Log base address in non-secure memory.
+
+- tpm_event_log_size [mandatory]
+    - value type: <u32>
+    - Event Log size.