Revert "vexpress_ca9x4: Enable use of correct DTB file and restore EFI loader."

Currently this causes failures of the platform when running the EFI
loader tests, so disable it for now.

This reverts commit af827140e5965e5bb2bcad1c53ca8419b428ff6d.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/vexpress_ca9x4_defconfig b/configs/vexpress_ca9x4_defconfig
index 6bd1f25..2119df6 100644
--- a/configs/vexpress_ca9x4_defconfig
+++ b/configs/vexpress_ca9x4_defconfig
@@ -34,4 +34,4 @@
 CONFIG_BAUDRATE=38400
 CONFIG_CONS_INDEX=0
 CONFIG_OF_LIBFDT=y
-CONFIG_DEFAULT_FDT_FILE="vexpress-v2p-ca9.dtb"
+# CONFIG_EFI_LOADER is not set