libfdt: fdt_check_full: Add can_assume(PERFECT) check

In this function from fdt_check.c we have (reasonably and as the name
implies) a number of checks on the DTB. However, there are cases where
we may wish to assume that we have been given a perfect DTB already and
do nothing here. Add a test for can_assume(PERFECT) as the first check
in this function and if true, perform no checks.

Signed-off-by: Tom Rini <trini@konsulko.com>
Message-ID: <20260526203022.4006434-1-trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

libfdt/fdt_check.c

@@ -21,6 +21,8 @@ int fdt_check_full(const void *fdt, size_t bufsize)
 	const char *propname;
 	bool expect_end = false;
 
+	if (can_assume(PERFECT))
+		return 0;
 	if (bufsize < FDT_V1_SIZE)
 		return -FDT_ERR_TRUNCATED;
 	if (bufsize < fdt_header_size(fdt))