multiboot: Refactor boot data validation, add version numbers

Instead of verifying the CRC before every access of the boot data,
verify the CRC once at startup and set a flag to indicate the boot
data is valid.

Also add a framework to support multiple boot protocol versions.
Firmware declares the maximum supported protocol version using a
version byte in the boot data header. The bootloader chooses the
highest version supported by it and the firmware when deciding
what boot protocol to use.

Change-Id: I810194625dc0833f026d2a23b8d64ed467fa6aca

apps/main.c

@@ -77,6 +77,7 @@
 #include "statusbar-skinned.h"
 #include "bootchart.h"
 #include "logdiskf.h"
+#include "bootdata.h"
 #if (CONFIG_PLATFORM & PLATFORM_ANDROID)
 #include "notification.h"
 #endif
@@ -445,6 +446,10 @@ static void init(void)
     core_allocator_init();
     kernel_init();
 
+#if defined(HAVE_BOOTDATA) && !defined(BOOTLOADER)
+    verify_boot_data();
+#endif
+
     /* early early early! */
     filesystem_init();