configs: am64x_evm_a53: Add Initial support

Add initial A53 defconfig support for AM64x SoCs.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
diff --git a/board/ti/am64x/MAINTAINERS b/board/ti/am64x/MAINTAINERS
index bb8c00c..d384a33 100644
--- a/board/ti/am64x/MAINTAINERS
+++ b/board/ti/am64x/MAINTAINERS
@@ -5,3 +5,4 @@
 F:	board/ti/am64x/
 F:	include/configs/am64x_evm.h
 F:	configs/am64x_evm_r5_defconfig
+F:	configs/am64x_evm_a53_defconfig