coverage: use boot state callbacks

Utilize the static boot state callback scheduling to initialize
and tear down the coverage infrastructure at the appropriate points.
The coverage initialization is performed at BS_PRE_DEVICE which is the
earliest point a callback can be called. The tear down occurs at the
2 exit points of ramstage: OS resume and payload boot.

Change-Id: Ie5ee51268e1f473f98fa517710a266e38dc01b6d
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/3135
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/x86/boot/acpi.c

@@ -36,7 +36,6 @@
 #if CONFIG_COLLECT_TIMESTAMPS
 #include <timestamp.h>
 #endif
-#include <coverage.h>
 
 /* FIXME: Kconfig doesn't support overridable defaults :-( */
 #ifndef CONFIG_HPET_MIN_TICKS
@@ -638,9 +637,6 @@ void acpi_resume(void *wake_vec)
 	/* Call mainboard resume handler first, if defined. */
 	if (mainboard_suspend_resume)
 		mainboard_suspend_resume();
-#if CONFIG_COVERAGE
-	coverage_exit();
-#endif
 	/* Tear down the caching of the ROM. */
 	if (disable_cache_rom)
 		disable_cache_rom();