Force Simple Mapping

Extended mapping sets the status bit indicating that it is extended on
the 63rd bit. For systems that can only access 32-bit, this won't work.
Use MappingTypeHints to use Simple for everything.

driver/device_buffer_mapper.cc

@@ -106,7 +106,7 @@ util::StatusOr<DeviceBuffer> DeviceBufferMapper::Map(const Buffer& buffer,
                                                      DmaDirection direction) {
   TRACE_SCOPE("DeviceBufferMapper::Map");
   if (buffer.IsValid()) {
-    return address_space_->MapMemory(buffer, direction, MappingTypeHint::kAny);
+    return address_space_->MapMemory(buffer, direction, MappingTypeHint::kSimple);
   }
   return DeviceBuffer();  // Invalid buffer.
 }

driver/mmio_driver.cc

@@ -435,7 +435,7 @@ util::StatusOr<MappedDeviceBuffer> MmioDriver::DoMapBuffer(
   if (buffer.IsValid()) {
     ASSIGN_OR_RETURN(auto device_buffer,
                      address_space_->MapMemory(buffer, direction,
-                                               MappingTypeHint::kExtended));
+                                               MappingTypeHint::kSimple));
     // TODO : this is dangerous: the std::bind captures a raw pointer to
     // the address space. This will break if executable registry outlives
     // address space in the driver. A better way is to at least use share_ptr