lib/program_loaders.c: Mark run_ramstage with __noreturn

This allows the compiler to optimize out code called after run_ramstage.

Also remove some die() statements in soc code as run_ramstage already
has a die_with_postcode statement.

Change-Id: Id8b841712661d3257b0dc67b509f97bdc31fcf6f
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65811
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/soc/amd/cezanne/romstage.c

@@ -25,5 +25,4 @@ void __noreturn romstage_main(void)
 	memmap_stash_early_dram_usage();
 
 	run_ramstage();
-	die("failed to load ramstage\n");
 }