drbd: stop defining __KERNEL_SYSCALLS__

__KERNEL_SYSCALLS__ hasn't been needed since Linux 2.6.19 so stop
defining it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Link: https://lore.kernel.org/r/20230601151646.1386867-1-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/drbd/drbd_main.c

@@ -37,7 +37,6 @@
 #include <linux/notifier.h>
 #include <linux/kthread.h>
 #include <linux/workqueue.h>
-#define __KERNEL_SYSCALLS__
 #include <linux/unistd.h>
 #include <linux/vmalloc.h>
 #include <linux/sched/signal.h>

drivers/block/drbd/drbd_receiver.c

@@ -27,7 +27,6 @@
 #include <uapi/linux/sched/types.h>
 #include <linux/sched/signal.h>
 #include <linux/pkt_sched.h>
-#define __KERNEL_SYSCALLS__
 #include <linux/unistd.h>
 #include <linux/vmalloc.h>
 #include <linux/random.h>