dif: Update spdk_dif_error structure to bump SO_VER forcefully

We will match enum spdk_dif_pi_format with the NVMe specification.

enum spdk_dif_pi_format was added a year ago. we need users to recompile
their application if they use enum spdk_dif_pi_format.

However, enum spdk_dif_pi_format was not used in any data structure and
ABIDIFF tool could not detect the change.

The change breaks ABI. Hence, we should bump SO_VER of lib/util in any
other way to notify the change to users.

The cleanest way to do that without hacking check_so_deps.sh is to add
a reserved field to spdk_dif_error structure.

Signed-off-by: Shuhei Matsumoto <smatsumoto@nvidia.com>
Change-Id: I7e12094bbe33f6c75780f09eb58d673d75752781
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/24182


Reviewed-by: Aleksey Marchuk <alexeymar@nvidia.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Ben Walker <ben@nvidia.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <jim.harris@samsung.com>