efi: Set RUN_64BIT correctly for the EFI app

The U-Boot EFI app can run as a 64-bit program, so set the Kconfig
correctly in that case. Make sure it doesn't build SPL, since there is
no need to switch from 32 to 64 bit when running.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 07be5cd..99e59d9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -32,8 +32,8 @@
 config X86_RUN_64BIT
 	bool "64-bit"
 	select X86_64
-	select SPL
-	select SPL_SEPARATE_BSS
+	select SPL if !EFI_APP
+	select SPL_SEPARATE_BSS if !EFI_APP
 	help
 	  Build U-Boot as a 64-bit binary with a 32-bit SPL. This is
 	  experimental and many features are missing. U-Boot SPL starts up,