fix: rename Matterhorn, Matterhorn ELP, and Klein CPUs

This patch renames the Matterhorn, Matterhorn ELP, and Klein CPUs to
Cortex A710, Cortex X2, and Cortex A510 respectively.

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I056d3114210db71c2840a24562b51caf2546e195
diff --git a/plat/arm/board/fvp/platform.mk b/plat/arm/board/fvp/platform.mk
index b58a0d2..10258ad 100644
--- a/plat/arm/board/fvp/platform.mk
+++ b/plat/arm/board/fvp/platform.mk
@@ -131,8 +131,8 @@
 					lib/cpus/aarch64/neoverse_e1.S		\
 					lib/cpus/aarch64/neoverse_v1.S		\
 					lib/cpus/aarch64/cortex_a78_ae.S	\
-					lib/cpus/aarch64/cortex_klein.S		\
-					lib/cpus/aarch64/cortex_matterhorn.S	\
+					lib/cpus/aarch64/cortex_a510.S		\
+					lib/cpus/aarch64/cortex_a710.S	\
 					lib/cpus/aarch64/cortex_makalu.S	\
 					lib/cpus/aarch64/cortex_makalu_elp_arm.S \
 					lib/cpus/aarch64/cortex_a65.S		\