arm: mach-k3: Move code specific to a SoC into that SoC's directory

Each SoC now has a directory in mach-k3, let's move the SoC specific
files into their respective directories.

Signed-off-by: Andrew Davis <afd@ti.com>
diff --git a/arch/arm/mach-k3/j721e/Makefile b/arch/arm/mach-k3/j721e/Makefile
new file mode 100644
index 0000000..982b88d
--- /dev/null
+++ b/arch/arm/mach-k3/j721e/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2024 Texas Instruments Incorporated - https://www.ti.com/
+#	Andrew Davis <afd@ti.com>
+
+obj-$(CONFIG_OF_SYSTEM_SETUP) += j721e_fdt.o
+obj-$(CONFIG_SPL_BUILD) += j721e_init.o