halide2isl.cc: extractAccess: drop redundant cast

The cast was apparently introduced because isl::aff does not currently
have an "eq_map" method.  However, the "eq_map" call was replaced
by an "eq_set" call 8a4d9f1 (halide2isl::extractAccesses: construct
accesses in parameter space, Mon Mar 26 14:50:33 2018 +0200), which
does appear as a method in isl:aff.  The cast is therefore no longer
needed.
Explicit casts make it more difficult to switch to templated isl types.

Author: Sven Verdoolaege

tc/core/halide2isl.cc

@@ -277,7 +277,7 @@ isl::map extractAccess(
     // ... equals the coordinate accessed as a function of the parameters.
     auto domainPoint = halide2isl::makeIslAffFromExpr(tensorSpace, args[i]);
     if (!domainPoint.is_null()) {
-      access = access.intersect(isl::pw_aff(domainPoint).eq_set(rangePoint));
+      access = access.intersect(domainPoint.eq_set(rangePoint));
     }
   }