Don't hardcode the super partition name.

If a device has logical partitions but does not use a partition called
"super", we will need this to be configurable. Note that the "slot"
argument is currently unused, but will be necessary for update_engine if
there are A and B super partitions.

Bug: 116608795
Test: super partition works
Change-Id: Ieb548a158faeb423f3561230f26d582325efbc6b
diff --git a/fastboot/device/commands.cpp b/fastboot/device/commands.cpp
index b7cafac..d952a25 100644
--- a/fastboot/device/commands.cpp
+++ b/fastboot/device/commands.cpp
@@ -27,6 +27,7 @@
 #include <android-base/unique_fd.h>
 #include <cutils/android_reboot.h>
 #include <ext4_utils/wipe.h>
+#include <fs_mgr.h>
 #include <liblp/builder.h>
 #include <liblp/liblp.h>
 #include <uuid/uuid.h>
@@ -307,7 +308,7 @@
 };
 
 PartitionBuilder::PartitionBuilder(FastbootDevice* device) {
-    auto super_device = FindPhysicalPartition(LP_METADATA_PARTITION_NAME);
+    auto super_device = FindPhysicalPartition(fs_mgr_get_super_partition_name());
     if (!super_device) {
         return;
     }