drm/i915/cmdparser: Check for SKIP descriptors first

If the command descriptor says to skip it, ignore checking for anyother
other conflict.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-37-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_cmd_parser.c

@@ -1046,6 +1046,9 @@ static bool check_cmd(const struct intel_engine_cs *engine,
 		      const bool is_master,
 		      bool *oacontrol_set)
 {
+	if (desc->flags & CMD_DESC_SKIP)
+		return true;
+
 	if (desc->flags & CMD_DESC_REJECT) {
 		DRM_DEBUG_DRIVER("CMD: Rejected command: 0x%08X\n", *cmd);
 		return false;