drm/i915: Expose I915_EXEC_RESOURCE_STREAMER flag and getparam

drm/i915: Expose I915_EXEC_RESOURCE_STREAMER flag and getparam

Ensures that the batch buffer is executed by the resource streamer.
And will let userspace know whether Resource Streamer is supported in
the kernel.

v2: Don't skip 1<<15 for the exec flags (Jani Nikula)
v3: Use HAS_RESOURCE_STREAMER macro for execbuf validation (Chris Wilson)

(from getparam patch)

v2: Update I915_PARAM_HAS_RESOURCE_STREAMER so it's after
    I915_PARAM_HAS_GPU_RESET.
v3: Only advertise RS support for hardware that supports it.
v4: Add HAS_RESOURCE_STREAMER() macro (Chris)

Testcase: igt/gem_exec_params
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Kenneth Graunke <kenneth@whitecape.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
[danvet: squash in getparam patch since it'd break bisect, suggested
by Chris.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>