Revert "hwc: Set ioprio for vsync thread"

Depends on libcutils support, which was removed in
https://review.lineageos.org/#/c/189293/.

exynos4/hal/libhwc/hwcomposer_vsync.cpp

@@ -17,7 +17,6 @@
 #include "hwcomposer.h"
 #include "hwcomposer_vsync.h"
 
-#include <cutils/iosched_policy.h>
 #include <cutils/threads.h>
 
 #include <utils/threads.h>
@@ -47,7 +46,6 @@ static void *hwc_vsync_thread(void *data)
     char thread_name[64] = HWC_VSYNC_THREAD_NAME;
     prctl(PR_SET_NAME, (unsigned long) &thread_name, 0, 0, 0);
     androidSetThreadPriority(0, HAL_PRIORITY_URGENT_DISPLAY);
-    android_set_rt_ioprio(0, 1);
 
     memset(buf, 0, sizeof(buf));