SurfaceTextureClient : Reset buffer size to 0 after setting geometry

Buffer size has to be reset to 0 after setting geometry , otherwise
the new request may get the buffer with wrong size.

CRs-Fixed: 337041
(cherry picked from commit 9b3ebedad4f53b7348135dac827392a39b01f69f)

Change-Id: Id9afe01c80912d3245c2f37ddac51f550c896dce