boot state: rebalance payload load vs actual boot

The notion of loading a payload in the current boot state
machine isn't actually loading the payload. The reason is
that cbfs is just walked to find the payload. The actual
loading and booting were occuring in selfboot(). Change this
balance so that loading occurs in one function and actual
booting happens in another. This allows for ample opportunity
to delay work until just before booting.

Change-Id: Ic91ed6050fc5d8bb90c8c33a44eea3b1ec84e32d
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/3139
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/lib/hardwaremain.c

@@ -198,6 +198,7 @@ static boot_state_t bs_write_tables(void *arg)
 static boot_state_t bs_payload_load(void *arg)
 {
 	void *payload;
+	void *entry;
 
 	timestamp_add_now(TS_LOAD_PAYLOAD);
 
@@ -206,15 +207,20 @@ static boot_state_t bs_payload_load(void *arg)
 	if (! payload)
 		die("Could not find a payload\n");
 
+	entry = selfload(get_lb_mem(), payload);
+
+	if (! entry)
+		die("Could not load payload\n");
+
 	/* Pass the payload to the next state. */
-	boot_states[BS_PAYLOAD_BOOT].arg = payload;
+	boot_states[BS_PAYLOAD_BOOT].arg = entry;
 
 	return BS_PAYLOAD_BOOT;
 }
 
-static boot_state_t bs_payload_boot(void *payload)
+static boot_state_t bs_payload_boot(void *entry)
 {
-	selfboot(get_lb_mem(), payload);
+	selfboot(entry);
 
 	printk(BIOS_EMERG, "Boot failed");
 	/* Returning from this state will fail because the following signals