Pointed FlashingPlan to Interface

Using interface for testing purposes

Bug: 194686221
Test: tested compilation
Change-Id: Ia9465c1f5673c249cdbc08a1a2432e8a603bd9cc
diff --git a/fastboot/fastboot.h b/fastboot/fastboot.h
index 2d79e42..009b3a1 100644
--- a/fastboot/fastboot.h
+++ b/fastboot/fastboot.h
@@ -99,7 +99,7 @@
     std::string current_slot;
     std::string secondary_slot;
 
-    fastboot::FastBootDriver* fb;
+    fastboot::IFastBootDriver* fb;
 };
 
 class FlashAllTool {