cleanup: Remove pointless assert(tarval_is_long(tv)).

The following get_tarval_long(tv) has the same assertion internally.

ir/be/ia32/x86_address_mode.c

@@ -288,7 +288,6 @@ tryit:
 						ir_mode   *mode         = get_irn_mode(and);
 						ir_tarval *all_one      = get_mode_all_one(mode);
 						ir_tarval *shift_mask   = tarval_shl(tarval_shr(all_one, shift_amount), shift_amount);
-						assert(tarval_is_long(shift_amount));
 						long       val          = get_tarval_long(shift_amount);
 
 						if (and_mask == shift_mask && val >= 0 && val <= 3) {

ir/opt/iropt.c

@@ -5265,7 +5265,6 @@ cmp_x_eq_0:
 					ir_tarval *c2 = get_Const_tarval(lr);
 					ir_tarval *c3 = get_Const_tarval(right);
 
-					assert(tarval_is_long(c1));
 					ir_mode *mode = get_irn_mode(left);
 					long     l1   = get_tarval_long(c1);
 					long     h2   = get_tarval_highest_bit(c2);