radeon: correct RADEON_GEM_WAIT_IDLE use

RADEON_GEM_WAIT_IDLE is declared DRM_IOW but libdrm
uses it with drmCommandWriteRead instead of drmCommandWrite
which leads to the ioctl being unmatched and returning an
error on at least OpenBSD.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Signed-off-by: Jonathan Gray <jsg@jsg.id.au>

radeon/radeon_bo_gem.c

@@ -211,7 +211,7 @@ static int bo_wait(struct radeon_bo_int *boi)
     memset(&args, 0, sizeof(args));
     args.handle = boi->handle;
     do {
-        ret = drmCommandWriteRead(boi->bom->fd, DRM_RADEON_GEM_WAIT_IDLE,
+        ret = drmCommandWrite(boi->bom->fd, DRM_RADEON_GEM_WAIT_IDLE,
 			      &args, sizeof(args));
     } while (ret == -EBUSY);
     return ret;