arm64: Replace strncmp with str_has_prefix

In commit b6b2735514bc
("tracing: Use str_has_prefix() instead of using fixed sizes")
the newly introduced str_has_prefix() was used
to replace error-prone strncmp(str, const, len).
Here fix codes with the same pattern.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: Will Deacon <will@kernel.org>
diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index 4f241cc..4decf16 100644
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c
@@ -29,7 +29,7 @@ static __init int numa_parse_early_param(char *opt)
 {
 	if (!opt)
 		return -EINVAL;
-	if (!strncmp(opt, "off", 3))
+	if (str_has_prefix(opt, "off"))
 		numa_off = true;
 
 	return 0;