arm: dts: k3-am64: Move to OF_UPSTREAM

Enable OF_UPSTREAM for AM64-EVM and SK-AM64 boards. Remove DT files that
are now available in dts/upstream. Update the appended files based on
version of latest OF_UPSTREAM sync point (v6.7-rc7).

Signed-off-by: Andrew Davis <afd@ti.com>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index a965a70..51c83ef 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -1418,9 +1418,7 @@
 dtb-$(CONFIG_SOC_K3_J784S4) += k3-am69-r5-sk.dtb \
 			       k3-j784s4-r5-evm.dtb
 
-dtb-$(CONFIG_SOC_K3_AM642) += k3-am642-evm.dtb \
-			      k3-am642-r5-evm.dtb \
-			      k3-am642-sk.dtb \
+dtb-$(CONFIG_SOC_K3_AM642) += k3-am642-r5-evm.dtb \
 			      k3-am642-r5-sk.dtb \
 			      k3-am642-phyboard-electra-rdk.dtb \
 			      k3-am642-r5-phycore-som-2gb.dtb