move mmu version bool into etnaviv_gpu struct

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
add to_bytes(..) helper

This little helper may look very stupid, but it helps
to keep track of places where we want to convert cmd stream
worlds to bytes. I think this makes the code a little bit
easier to understand. As the to_bytes(..) is a static
inline function there is no impact on performance.

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
rename words back to offset

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
store the virtual address of the last WAIT

The WAIT/LINK combo is quite important for queuing a new cmd buffer.
In the last step of this process we patch the last WAIT to a LINK.

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
make use of buffer->last_wait in etnaviv_buffer_queue(..)

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>