completion: zsh: simplify file_direct

It's exactly the same as __gitcomp_file() with no prefix.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.zsh

@@ -124,9 +124,7 @@ __gitcomp_nl_append ()
 
 __gitcomp_file_direct ()
 {
-	emulate -L zsh
-
-	compadd -f -- ${(f)1} && _ret=0
+	__gitcomp_file "$1" ''
 }
 
 __gitcomp_file ()