meta-signing-key, meta-efi-secure-boot: Rework for dependencies

The content of meta-signing-key depends on a few recipes within
meta-efi-secure-boot.  However, meta-signing-key can be used without
meta-efi-secure-boot if we move libsign and sbsigntool over.  Doing this will
also provide a more correct set of dependencies as we cannot say that both
layers depend on eachother.  While doing this, within meta-signing-key only
depend on content from meta-efi-secure-boot if the efi-secure-boot
DISTRO_FEATURE is set.

Signed-off-by: Tom Rini <trini@konsulko.com>

meta-signing-key/classes/user-key-store.bbclass

@@ -2,7 +2,7 @@ DEPENDS_append_class-target += "\
     sbsigntool-native \
     libsign-native \
     openssl-native \
-    efitools-native \
+    ${@bb.utils.contains("DISTRO_FEATURES", "efi-secure-boot", "efitools-native", "", d)} \
 "
 
 USER_KEY_SHOW_VERBOSE = "1"