drm/xe: Split lrc seqno fence creation up

drm/xe: Split lrc seqno fence creation up

Since sometimes a lock is required to initialize a seqno fence,
and it might be desirable not to hold that lock while performing
memory allocations, split the lrc seqno fence creation up into an
allocation phase and an initialization phase.

Since lrc seqno fences under the hood are hw_fences, do the same
for these and remove the xe_hw_fence_create() function since it
is not used anymore.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240527135912.152156-3-thomas.hellstrom@linux.intel.com