treewide: Drop image_header_t typedef

This is not needed and we should avoid typedefs. Use the struct instead
and rename it to indicate that it really is a legacy struct.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/mips/mach-jz47xx/jz4780/jz4780.c b/arch/mips/mach-jz47xx/jz4780/jz4780.c
index a57ec78..4c40bd8 100644
--- a/arch/mips/mach-jz47xx/jz4780/jz4780.c
+++ b/arch/mips/mach-jz47xx/jz4780/jz4780.c
@@ -30,7 +30,7 @@
 	typedef void __noreturn (*image_entry_noargs_t)(void);
 	struct mmc *mmc;
 	unsigned long count;
-	struct image_header *header;
+	struct legacy_img_hdr *header;
 	int ret;
 
 	/* Set global data pointer */
@@ -58,8 +58,8 @@
 	if (ret)
 		hang();
 
-	header = (struct image_header *)(CONFIG_SYS_TEXT_BASE -
-					 sizeof(struct image_header));
+	header = (struct legacy_img_hdr *)(CONFIG_SYS_TEXT_BASE -
+					 sizeof(struct legacy_img_hdr));
 
 	count = blk_dread(mmc_get_blk_desc(mmc),
 			  CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,