treewide: Drop bootm_headers_t typedef

This is not needed and we should avoid typedefs. Use the struct instead.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/synopsys/hsdk/hsdk.c b/board/synopsys/hsdk/hsdk.c
index 226fbba..4308c7e 100644
--- a/board/synopsys/hsdk/hsdk.c
+++ b/board/synopsys/hsdk/hsdk.c
@@ -844,7 +844,7 @@
 	return 0;
 }
 
-int board_prep_linux(bootm_headers_t *images)
+int board_prep_linux(struct bootm_headers *images)
 {
 	int ret, ofst;
 	char mask[15];