Add support for TBBR using ECDSA keys in ARM platforms

    - fixed compile error when KEY_ALG=ecdsa
    - add new option ecdsa for TF_MBEDTLS_KEY_ALG
    - add new option devel_ecdsa for ARM_ROTPK_LOCATION
    - add ecdsa key at plat/arm/board/common/rotpk/
    - reduce the mbedtls heap memory size to 13k

Change-Id: I3f7a6170af93fdbaaa7bf2fffb4680a9f6113c13
Signed-off-by: Qixiang Xu <qixiang.xu@arm.com>
diff --git a/docs/user-guide.rst b/docs/user-guide.rst
index 1ff080d..67af425 100644
--- a/docs/user-guide.rst
+++ b/docs/user-guide.rst
@@ -643,6 +643,11 @@
       ``arm_rotpk_rsa.der``, located in ``plat/arm/board/common/rotpk``. To use
       this option, ``arm_rotprivk_rsa.pem`` must be specified as ``ROT_KEY`` when
       creating the certificates.
+   -  ``devel_ecdsa`` : return a development public key hash embedded in the BL1
+      and BL2 binaries. This hash has been obtained from the ECDSA public key
+      ``arm_rotpk_ecdsa.der``, located in ``plat/arm/board/common/rotpk``. To use
+      this option, ``arm_rotprivk_ecdsa.pem`` must be specified as ``ROT_KEY``
+      when creating the certificates.
 
 -  ``ARM_TSP_RAM_LOCATION``: location of the TSP binary. Options:
 
@@ -990,6 +995,10 @@
       in the ARM platform port. The private/public RSA key pair may be
       found in ``plat/arm/board/common/rotpk``.
 
+   -  ``ARM_ROTPK_LOCATION=devel_ecdsa``: use the ROTPK hash that is hardcoded
+      in the ARM platform port. The private/public ECDSA key pair may be
+      found in ``plat/arm/board/common/rotpk``.
+
    Example of command line using RSA development keys:
 
    ::