devfs: casts as size_t before comparing.

* error: comparison between signed and unsigned integer expressions.

src/system/kernel/device_manager/devfs.cpp

@@ -487,7 +487,7 @@ translate_partition_access(devfs_partition* partition, off_t& offset,
 	ASSERT(offset >= 0);
 	ASSERT(offset < partition->info.size);
 
-	size = min_c(size, partition->info.size - offset);
+	size = min_c(size, (size_t)(partition->info.size - offset));
 	offset += partition->info.offset;
 }