x86: Rename efi-x86 target to efi-x86_app

To avoid confusion, let's rename the efi-x86 target to efi-x86_app.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/efi/Makefile b/arch/x86/cpu/efi/Makefile
index 32c2dde..9716a4e 100644
--- a/arch/x86/cpu/efi/Makefile
+++ b/arch/x86/cpu/efi/Makefile
@@ -3,7 +3,7 @@
 # Copyright (c) 2015 Google, Inc
 
 ifdef CONFIG_EFI_APP
-obj-y += efi.o
+obj-y += app.o
 obj-y += sdram.o
 endif
 
diff --git a/arch/x86/cpu/efi/efi.c b/arch/x86/cpu/efi/app.c
similarity index 100%
rename from arch/x86/cpu/efi/efi.c
rename to arch/x86/cpu/efi/app.c