io_uring: fix incorrect __kernel_rwf_t cast

Currently 'make C=1 fs/io_uring.o' generates sparse warning:

  CHECK   fs/io_uring.c
fs/io_uring.c: note: in included file (through
include/trace/trace_events.h, include/trace/define_trace.h, i
nclude/trace/events/io_uring.h):
./include/trace/events/io_uring.h:488:1:
 warning: incorrect type in assignment (different base types)
    expected unsigned int [usertype] op_flags
    got restricted __kernel_rwf_t const [usertype] rw_flags

This happen on cast of sqe->rw_flags which is defined as __kernel_rwf_t,
this type is bitwise and requires __force attribute for any casts.
However rw_flags is a member of the union, and its access can be safely
replaced by using of its neighbours, so let's use poll32_events to fix
the sparse warning.
Signed-off-by: Vasily Averin <vvs@openvz.org>
Link: https://lore.kernel.org/r/6f009241-a63f-ae43-a04b-62841aaef293@openvz.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

include/trace/events/io_uring.h

@@ -520,7 +520,7 @@ TRACE_EVENT(io_uring_req_failed,
 		__entry->off		= sqe->off;
 		__entry->addr		= sqe->addr;
 		__entry->len		= sqe->len;
-		__entry->op_flags	= sqe->rw_flags;
+		__entry->op_flags	= sqe->poll32_events;
 		__entry->buf_index	= sqe->buf_index;
 		__entry->personality	= sqe->personality;
 		__entry->file_index	= sqe->file_index;