x86: efi: Refactor the directory of EFI app and payload support

At present the EFI application and payload support codes in the x86
directory is distributed in a hybrid way. For example, the Kconfig
options for both app and payload are in arch/x86/lib/efi/Kconfig,
but the source codes in the same directory get built only for
CONFIG_EFI_STUB.

This refactors the codes by consolidating all the EFI support codes
into arch/x86/cpu/efi, just like other x86 targets.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 18c7fb2..a1c18d2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -112,6 +112,7 @@
 source "arch/x86/cpu/broadwell/Kconfig"
 source "arch/x86/cpu/coreboot/Kconfig"
 source "arch/x86/cpu/ivybridge/Kconfig"
+source "arch/x86/cpu/efi/Kconfig"
 source "arch/x86/cpu/qemu/Kconfig"
 source "arch/x86/cpu/quark/Kconfig"
 source "arch/x86/cpu/queensbay/Kconfig"
@@ -772,6 +773,4 @@
 	  Increse it if the default size does not fit the board's needs.
 	  This is most likely due to a large ACPI DSDT table is used.
 
-source "arch/x86/lib/efi/Kconfig"
-
 endmenu