libvfio-user: update submodule

The new commits eliminate `1.45%nvmf_tgt[.] vfu_log`
CPU profile when building in release mode.

Change-Id: I6347949a31f61ecfc619435ac3743f8d9dab3603
Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/14122


Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Dong Yi <dongx.yi@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>