Add force_writable to MapPartitionOnDeviceMapper

In sideloading we will map source partitions with
force_writable = false.

Test: manual sideloading
Bug: 117101719

Change-Id: I7629b8ecce07a9bd2c9e24ac6b64617386067ca5
diff --git a/boot_control_android.cc b/boot_control_android.cc
index 8eafdce..12296d7 100644
--- a/boot_control_android.cc
+++ b/boot_control_android.cc
@@ -298,7 +298,7 @@
       super_device, builder.get(), target_slot);
 }
 
-// Unmap all partitions, and remap partitions.
+// Unmap all partitions, and remap partitions as writable.
 bool Remap(DynamicPartitionControlInterface* dynamic_control,
            const string& super_device,
            Slot target_slot,
@@ -318,6 +318,7 @@
               super_device,
               partition.name + target_suffix,
               target_slot,
+              true /* force writable */,
               &map_path)) {
         return false;
       }