kboot: Call enumerate_memory_arch()

Now that all architectures provide this, enumerate the platform's memory
before we go to interact(). This needs to be done only once, but relies
on our ability to open host: files on some platforms, so it needs to be
done after devinit().

Sponsored by:		Netflix
Reviewed by:		tsoome, kevans
Differential Revision:	https://reviews.freebsd.org/D38251

stand/kboot/main.c

@@ -256,6 +256,7 @@ main(int argc, const char **argv)
 	setenv("LINES", "24", 1);
 
 	memory_limits();
+	enumerate_memory_arch();
 
 	/*
 	 * Find acpi, if it exists