liburing.h: fix 32-bit compile warning
liburing.h: fix 32-bit compile warning

Cast 'ts' to uintptr_t, to avoid having the compiler complain about
casting it to a 64-bit size.

../src/include/liburing.h: In function ‘io_uring_prep_timeout_update’:
../src/include/liburing.h:342:42: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
  342 |     (void *)(unsigned long)user_data, 0, (__u64)ts);
      |                                          ^

Signed-off-by: Jens Axboe <cd8c6775e60d6f67a6984377324e5290df3d5358@kernel.dk>

axboe/liburing,axboe/liburing,axboe/liburing