freedreno: un-invert SGE/SLT logic

No functional change, but less confusing this way.

Signed-off-by: Rob Clark <robdclark@gmail.com>
freedreno: resource_transfer fixes

We need to keep track if the buffer has pending draw operations that
haven't yet been submitted, or haven't yet completed, so that we can
implement flush_region() properly.  Also fix the offset calculation.
This fixes some of the glReadPixels() problems.

Signed-off-by: Rob Clark <robdclark@gmail.com>
freedreno: scissor vs gmem2mem fix

Don't let scissor state inherited from the last draw call affect
gmem2mem.  Otherwise we could skip transferring back to system memory
parts that had been updated in earlier draw calls in the same batch.

Signed-off-by: Rob Clark <robdclark@gmail.com>