drm/xe/vf: Fix fs_reclaim warning with CCS save/restore BB allocation

CCS save/restore batch buffers are attached during BO allocation and
detached during BO teardown. The shrinker triggers xe_bo_move(), which is
used for both allocation and deletion paths.

When BO allocation and shrinking occur concurrently, a circular locking
dependency involving fs_reclaim and swap_guard can occur, leading to a
deadlock such as:

*===============================================================*
*    WARNING: possible circular locking dependency detected	*
*---------------------------------------------------------------*
*								*
*      CPU0                    CPU1				*
*      ----                    ----				*
* lock(fs_reclaim);						*
*                              lock(&sa_manager->swap_guard);	*
*                              lock(fs_reclaim);		*
* lock(&sa_manager->swap_guard);				*
*								*
* *** DEADLOCK ***						*
*===============================================================*

To avoid this, the BB pointer and SA are allocated using xe_bb_alloc()
before taking lock and SA is initialized using xe_bb_init() preventing
reclaim from being invoked in this context.

Fixes: 864690cf4dd62 ("drm/xe/vf: Attach and detach CCS copy commands with BO")
Signed-off-by: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Maarten Lankhorst <dev@lankhorst.se>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20260220055519.2485681-7-satyanarayana.k.v.p@intel.com

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