feat: add el3 attestation token signing

This adds build and coverity coverage for the new build option
RMMD_ENABLE_EL3_TOKEN_SIGN.

Change-Id: Ib9405c5b33f2885b8aefa450106a2804376e1ba0
Signed-off-by: Raghu Krishnamurthy <raghupathyk@nvidia.com>
diff --git a/tf_config/fvp-rme-el3-token-sign b/tf_config/fvp-rme-el3-token-sign
new file mode 100644
index 0000000..3974be6
--- /dev/null
+++ b/tf_config/fvp-rme-el3-token-sign
@@ -0,0 +1,5 @@
+CROSS_COMPILE=aarch64-none-elf-
+PLAT=fvp
+ENABLE_RME=1
+FVP_HW_CONFIG_DTS=fdts/fvp-base-gicv3-psci-1t.dts
+RMMD_ENABLE_EL3_TOKEN_SIGN=1