Prevent crash on modulo by zero

1937095 "Prevent crash on division by zero" fixed a crash when attempting
a division by zero using the / operator in a dts.  However, it missed the
precisely equivalent crash with the % (modulus) operator.  This patch fixes
the oversight.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

tests/division-by-zero.dts

@@ -1,5 +1,6 @@
 /dts-v1/;
 
 / {
-	prop = < (1/0) >;
+	prop-div = < (1/0) >;
+	prop-mod = < (1%0) >;
 };