drm/i915/lrc: Only set RS ctx enable in ctx control reg if there is a RS

The driver should only set the "RS context enable" bit in the context
image if we plan to use the resource streamer.
Reviewed-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NMichel Thierry <michel.thierry@intel.com>
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1456393738-35608-1-git-send-email-michel.thierry@intel.com

drivers/gpu/drm/i915/intel_lrc.c

@@ -2382,7 +2382,8 @@ populate_lr_context(struct intel_context *ctx, struct drm_i915_gem_object *ctx_o
 	ASSIGN_CTX_REG(reg_state, CTX_CONTEXT_CONTROL, RING_CONTEXT_CONTROL(ring),
 		       _MASKED_BIT_ENABLE(CTX_CTRL_INHIBIT_SYN_CTX_SWITCH |
 					  CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT |
-					  CTX_CTRL_RS_CTX_ENABLE));
+					  (HAS_RESOURCE_STREAMER(dev) ?
+					    CTX_CTRL_RS_CTX_ENABLE : 0)));
 	ASSIGN_CTX_REG(reg_state, CTX_RING_HEAD, RING_HEAD(ring->mmio_base), 0);
 	ASSIGN_CTX_REG(reg_state, CTX_RING_TAIL, RING_TAIL(ring->mmio_base), 0);
 	/* Ring buffer start address is not known until the buffer is pinned.