This is largely a rewrite of the Host1x channel allocation code, bringing
several changes:

- The previous code could deadlock due to an interaction
  between the 'reflock' mutex and CDMA timeout handling.
  This gets rid of the mutex.
- Support for more than 32 channels, required for Tegra186
- General refactoring, including better encapsulation
  of channel ownership handling into channel.c
Signed-off-by: NMikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: NDmitry Osipenko <digetx@gmail.com>
Tested-by: NDmitry Osipenko <digetx@gmail.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>