program loading: add prog_run() function

The prog_run() function abstracts away what is required
for running a given program. Within it, there are 2
calls: 1. platform_prog_run() and 2. arch_prog_run().
The platform_prog_run() allows for a chipset to intercept
a program that will be run. This allows for CPU switching
as currently needed in t124 and t132.

Change-Id: I22a5dd5bfb1018e7e46475e47ac993a0941e2a8c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/8846
Tested-by: build bot (Jenkins)
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Marc Jones <marc.jones@se-eng.com>
diff --git a/src/arch/mips/boot.c b/src/arch/mips/boot.c
index 6e12d10..ebc45bb 100644
--- a/src/arch/mips/boot.c
+++ b/src/arch/mips/boot.c
@@ -20,7 +20,12 @@
 #include <arch/stages.h>
 #include <program_loading.h>
 
-void arch_payload_run(const struct payload *payload)
+void arch_prog_run(struct prog *prog)
 {
-	stage_exit(prog_entry(&payload->prog));
+	stage_exit(prog_entry(prog));
+}
+
+void arch_payload_run(struct payload *payload)
+{
+	arch_prog_run(&payload->prog);
 }