drm/xe/pf: Fix MMIO access using PF view instead of VF view during migration

drm/xe/pf: Fix MMIO access using PF view instead of VF view during migration

pf_migration_mmio_save() and pf_migration_mmio_restore() initialize a
local VF-specific MMIO view via xe_mmio_init_vf_view() but then pass
&gt->mmio (the PF base) to all xe_mmio_read32()/xe_mmio_write32()
calls instead of the local &mmio. This causes the PF own SW flag
registers to be saved/restored rather than the target VF registers,
silently corrupting migration state.

Use the VF MMIO view for all register accesses, matching the correct
pattern used in pf_clear_vf_scratch_regs().

Fixes: b7c1b990f719 ("drm/xe/pf: Handle MMIO migration data as part of PF control")
Cc: Michał Winiarski <michal.winiarski@intel.com>
Assisted-by: Claude:claude-opus-4.6
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
Link: https://patch.msgid.link/20260429192259.4009211-1-shuicheng.lin@intel.com
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
(cherry picked from commit 7d9c39cfb31ff389490ca1308767c2807a9829a6)
Signed-off-by: Matthew Brost <matthew.brost@intel.com>