drm/amdkfd: Add missing gfx11 MQD manager callbacks

mqd_stride function was introduced in commit 2f77b9a2


("drm/amdkfd: Update MQD management on multi XCC setup")
but not assigned for gfx11. Fixes a NULL dereference in debugfs.

Signed-off-by: Jay Cornwall <jay.cornwall@amd.com>
Signed-off-by: Harish Kasiviswanathan <Harish.Kasiviswanathan@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>