ExifInterface: Fix function for image size update

Existing code assumes that the primary image data is correctly placed.
Since this may be a mistaken assumption, this CL checks the
NewSubfilType value and updates the image size values only if the
tag value equals the original resolution image.

Bug: 29409358
Change-Id: I51cffba870ee29d76118b4c8b72290d1010c6462