player, ta: remove use of an old macro

I thought that would make a nice idiom, but it ended up being useless or
clunky.

player/main.c

@@ -264,7 +264,7 @@ struct MPContext *mp_create(void)
         .last_chapter = -2,
         .term_osd_contents = talloc_strdup(mpctx, ""),
         .osd_progbar = { .type = -1 },
-        .playlist = talloc_struct(mpctx, struct playlist, {0}),
+        .playlist = talloc_zero(mpctx, struct playlist),
         .dispatch = mp_dispatch_create(mpctx),
         .playback_abort = mp_cancel_new(mpctx),
         .thread_pool = mp_thread_pool_create(mpctx, 0, 1, 30),

ta/ta_talloc.h

@@ -156,7 +156,4 @@ char *ta_talloc_asprintf_append_buffer(char *s, const char *fmt, ...) TA_PRF(2,
         : false                                     \
     )
 
-#define talloc_struct(ctx, type, ...) \
-    talloc_memdup(ctx, &(type) TA_EXPAND_ARGS(__VA_ARGS__), sizeof(type))
-
 #endif