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
1 file changed