Add reflexivity for equality to the uPred hint DB.

algebra/upred.v

@@ -982,5 +982,5 @@ Hint Resolve and_intro and_elim_l' and_elim_r' : I.
 Hint Resolve always_mono : I.
 Hint Resolve sep_elim_l' sep_elim_r' sep_mono : I.
 Hint Immediate True_intro False_elim : I.
-Hint Immediate iff_refl : I.
+Hint Immediate iff_refl eq_refl : I.
 End uPred.