drm/i915: Use HAS_CSR instead of gen number on DMC load.

Since we have HAS_CSR tied to the platform definition
let's use this instead of checking per platform.

One less thing to worry when adding support to new platforms.
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Animesh Manna<animesh.manna@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1497047175-27250-14-git-send-email-rodrigo.vivi@intel.com

drivers/gpu/drm/i915/intel_csr.c

@@ -241,7 +241,7 @@ void intel_csr_load_program(struct drm_i915_private *dev_priv)
 	u32 *payload = dev_priv->csr.dmc_payload;
 	uint32_t i, fw_size;
 
-	if (!IS_GEN9(dev_priv)) {
+	if (!HAS_CSR(dev_priv)) {
 		DRM_ERROR("No CSR support available for this platform\n");
 		return;
 	}