gpu: host1x: External timeout/cancellation for fences

Currently all fences have a 30 second timeout to ensure they are
cleaned up if the fence never completes otherwise. However, this
one size fits all solution doesn't actually fit in every case,
such as syncpoint waiting where we want to be able to have timeouts
longer than 30 seconds. As such, we want to be able to give control
over fence cancellation to the caller (and maybe eventually get rid
of the internal timeout altogether).

Here we add this cancellation mechanism by essentially adding a
function for entering the timeout path by function call, and changing
the syncpoint wait function to use it.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

gpu: host1x: Rewrite syncpoint interrupt handling

Move from the old, complex intr handling code to a new implementation
based on dma_fences. While there is a fair bit of churn to get there,
the new implementation is much simpler and likely faster as well due
to allowing signaling directly from interrupt context.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

gpu: host1x: Add DMA fence implementation

Add an implementation of dma_fences based on syncpoints. Syncpoint
interrupts are used to signal fences. Additionally, after
software signaling has been enabled, a 30 second timeout is started.
If the syncpoint threshold is not reached within this period,
the fence is signalled with an -ETIMEDOUT error code. This is to
allow fences that would never reach their syncpoint threshold to
be cleaned up. The timeout can potentially be removed in the future
after job tracking code has been refactored.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>