base: efitools: check if we have the keys in place

Instaed of faling with a python exception we can check if we have
all keys reqired and fail with a useful message if not.

Signed-off-by: Jose Quaresma <jose.quaresma@foundries.io>

meta-lmp-base/recipes-bsp/efitools/efitools_git.bb

@@ -42,10 +42,15 @@ python do_prepare_local_auths() {
     dir = d.expand('${UEFI_SIGN_KEYDIR}/')
 
     import shutil
+    import os
 
     # Use auths already generated by the user
     for _ in ('PK', 'KEK', 'DB', 'DBX', 'noPK', 'noKEK'):
-        shutil.copyfile(dir + _ + '.auth', d.expand('${S}/') + _ + '.auth')
+        file = _ + '.auth'
+        src = dir + file
+        if not os.path.isfile(src):
+            bb.fatal("File '%s' not found!" % src)
+        shutil.copyfile(src, d.expand('${S}/') + file)
 
 }
 addtask prepare_local_auths after do_configure before do_compile