Camera3: Unmap buffers after stop reprocess stream

This makes sure buffers are not unmapped before stream is turned
off.

BUG=24195824
BUG=24416207
LACAM-972
LACAM-1372

Ack by Shuzhen Wang

Change-Id: Iba17ffe2458e37e5851d57daeb58c9f77ad28281
diff --git a/QCamera2/HAL3/QCamera3Channel.cpp b/QCamera2/HAL3/QCamera3Channel.cpp
index 9147dbd..7d27d0d 100644
--- a/QCamera2/HAL3/QCamera3Channel.cpp
+++ b/QCamera2/HAL3/QCamera3Channel.cpp
@@ -3593,12 +3593,12 @@
     ATRACE_CALL();
     int32_t rc = NO_ERROR;
 
-    unmapOfflineBuffers(true);
-
     rc = QCamera3Channel::stop();
 
     rc != m_camOps->stop_channel(m_camHandle, m_handle);
 
+    unmapOfflineBuffers(true);
+
     return rc;
 }