feat(cpu): add library support for Poseidon CPU

This patch adds the basic CPU library code to support the Poseidon CPU
in TF-A. Poseidon is derived from HunterELP core, an implementation of
v9.2 architecture. Currently, Hunter CPU the predecessor to HunterELP,
is supported in TF-A. Accordingly the Hunter CPU library code has been
as the base and adapted here.

Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: I406b4de156a67132e6a5523370115aaac933f18d
diff --git a/plat/arm/board/fvp/platform.mk b/plat/arm/board/fvp/platform.mk
index e184c3f..a24a2e5 100644
--- a/plat/arm/board/fvp/platform.mk
+++ b/plat/arm/board/fvp/platform.mk
@@ -143,7 +143,8 @@
 					lib/cpus/aarch64/cortex_a78c.S		\
 					lib/cpus/aarch64/cortex_hayes.S		\
 					lib/cpus/aarch64/cortex_hunter.S	\
-					lib/cpus/aarch64/cortex_x2.S
+					lib/cpus/aarch64/cortex_x2.S		\
+					lib/cpus/aarch64/neoverse_poseidon.S
 	endif
 	# AArch64/AArch32 cores
 	FVP_CPU_LIBS	+=	lib/cpus/aarch64/cortex_a55.S		\