MTP: Fix getThumbnail

The thumbnail size was not being passed to the MTP stack so getThumbnail
was returning zero length data.

Bug: 13747419

Change-Id: I309d35b5c46ab5f631c0dcb5981f7896bb5a2ed5

media/jni/android_mtp_MtpDatabase.cpp

diff --git a/media/jni/android_mtp_MtpDatabase.cpp b/media/jni/android_mtp_MtpDatabase.cpp
index 067e7a6..f8fb144 100644
--- a/media/jni/android_mtp_MtpDatabase.cpp
+++ b/media/jni/android_mtp_MtpDatabase.cpp
@@ -849,6 +849,7 @@
                 result = malloc(exifdata->size);
                 if (result) {
                     memcpy(result, exifdata->data, exifdata->size);
+                    outThumbSize = exifdata->size;
                 }
             }
             exif_data_unref(exifdata);