surfaceflinger: fix build for devices not using hwc2

HWComposer* DisplayUtils::getHWCInstance(

                        const sp<SurfaceFlinger>& flinger,

                        HWComposer::EventHandler& /* handler */) {

                        HWComposer::EventHandler& handler) {

#if defined(QTI_BSP) && !defined(USE_HWC2)

    if(sUseExtendedImpls) {

        return new ExHWComposer(flinger, handler);

    }

#elif defined(USE_HWC2)

#endif

#if defined(USE_HWC2)

    (void)handler;

    return new HWComposer(flinger);

#else

    return new HWComposer(flinger, handler);