arm: mach-k3: Move ARM64 specific code into new arm64 directory

Like we did with R5, move ARM64 code into a specific directory to make
it clear what code is only meant to run on each core type.

Signed-off-by: Andrew Davis <afd@ti.com>
diff --git a/arch/arm/mach-k3/arm64/Makefile b/arch/arm/mach-k3/arm64/Makefile
new file mode 100644
index 0000000..f3d322e
--- /dev/null
+++ b/arch/arm/mach-k3/arm64/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
+
+obj-y += arm64-mmu.o
+obj-y += cache.o