mlx5_core: Re-add MLX5_DEV_CAP_FLAG_ON_DMND_PG flag

In commit 0c7aac854f52 ("net/mlx5_core: Remove unused dev cap enum
fields"), the flag MLX5_DEV_CAP_FLAG_ON_DMND_PG was removed.
Unfortunately the on-demand paging changes actually use it, so re-add
the missing flag.

Signed-off-by: Roland Dreier <roland@purestorage.com>

include/linux/mlx5/device.h

@@ -234,6 +234,7 @@ enum {
 	MLX5_DEV_CAP_FLAG_APM		= 1LL << 17,
 	MLX5_DEV_CAP_FLAG_ATOMIC	= 1LL << 18,
 	MLX5_DEV_CAP_FLAG_BLOCK_MCAST	= 1LL << 23,
+	MLX5_DEV_CAP_FLAG_ON_DMND_PG	= 1LL << 24,
 	MLX5_DEV_CAP_FLAG_CQ_MODER	= 1LL << 29,
 	MLX5_DEV_CAP_FLAG_RESIZE_CQ	= 1LL << 30,
 	MLX5_DEV_CAP_FLAG_DCT		= 1LL << 37,