boot: Create a function for final pre-boot steps

There are various functions which announce that booting is imminent and
do related preparation. Most of these are arch-specific.

In practice, most archs do the a similar thing. It would be better to
have a common function, with perhaps some events for things that are
really arch- and board-specific.

Create a new function for this. For now, nothing uses it.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/bootm.h

@@ -16,6 +16,16 @@ struct cmd_tbl;
 #define BOOTM_ERR_OVERLAP		(-2)
 #define BOOTM_ERR_UNIMPLEMENTED	(-3)
 
+/**
+ * enum bootm_final_t - flags to control bootm_final()
+ *
+ * @BOOTM_FINAL_FAKE: true to do everything except actually boot; it then
+ *	returns to the caller
+ */
+enum bootm_final_t {
+	BOOTM_FINAL_FAKE	= BIT(0),
+};
+
 /**
  * struct bootm_info() - information used when processing images to boot
  *
@@ -375,4 +385,11 @@ void zimage_dump(struct bootm_info *bmi, bool show_cmdline);
  */
 int bootm_boot_start(ulong addr, const char *cmdline);
 
+/**
+ * bootm_final() - Announce and do cleanup before boot
+ *
+ * @flags: Flags to control what this function does
+ */
+void bootm_final(enum bootm_final_t flags);
+
 #endif