vdpa/mlx5: Expose descriptor group mkey hw capability

Necessary for improved live migration flow. Actual support will be added
in a downstream patch.

Reviewed-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Link: https://lore.kernel.org/r/20230928164550.980832-3-dtatulea@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

Author: dtatulea

include/linux/mlx5/mlx5_ifc.h

@@ -1231,7 +1231,13 @@ struct mlx5_ifc_virtio_emulation_cap_bits {
 	u8         max_emulated_devices[0x8];
 	u8         max_num_virtio_queues[0x18];
 
-	u8         reserved_at_a0[0x60];
+	u8         reserved_at_a0[0x20];
+
+	u8	   reserved_at_c0[0x13];
+	u8         desc_group_mkey_supported[0x1];
+	u8         reserved_at_d4[0xc];
+
+	u8         reserved_at_e0[0x20];
 
 	u8         umem_1_buffer_param_a[0x20];