efi_loader: Disable miniapps on sandbox

In the sandbox environment we can not easily build efi stub binaries
right now, so let's disable the respective test cases for the efi
selftest suite.

Signed-off-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/lib/efi_selftest/Makefile b/lib/efi_selftest/Makefile
index 4fe404d..bf5c819 100644
--- a/lib/efi_selftest/Makefile
+++ b/lib/efi_selftest/Makefile
@@ -41,7 +41,7 @@
 
 # TODO: As of v2018.01 the relocation code for the EFI application cannot
 # be built on x86_64.
-ifeq ($(CONFIG_X86_64),)
+ifeq ($(CONFIG_X86_64)$(CONFIG_SANDBOX),)
 
 ifneq ($(CONFIG_CMD_BOOTEFI_SELFTEST),)