gpu: ion: Don't call ion_buffer_put on error path

If dma_buf_fd fails, the dma_buf needs to be cleaned up by
calling dma_buf_put. dma_buf_put will call ion_dma_buf_release
which in turn calls ion_buffer_put to clean up the buffer
reference. Calling ion_buffer_put after dma_buf_put drops the
reference count by one more which is incorrect. Fix this by
getting rid of the extra ion_buffer_put call.

Change-Id: Ieb3a7b781bf2dc299c45384dbf0a12d186adeb22
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>