fastboot driver: Avoid use after std::move()

Test: TreeHugger
Change-Id: I2857f6d6384c8c80809f21202dbbbfc9ed71beeb
diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index 94efeea..e1bf984 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -995,7 +995,7 @@
         die("Failed writing to modified vbmeta");
     }
     buf->fd = std::move(fd);
-    lseek(fd, 0, SEEK_SET);
+    lseek(buf->fd, 0, SEEK_SET);
 }
 
 static bool has_vbmeta_partition() {
@@ -1063,7 +1063,7 @@
     }
     buf->fd = std::move(fd);
     buf->sz = partition_size;
-    lseek(fd, 0, SEEK_SET);
+    lseek(buf->fd, 0, SEEK_SET);
 }
 
 static void flash_buf(const std::string& partition, struct fastboot_buffer *buf)