drm/xe: Simplify pinned bo iteration

drm/xe: Simplify pinned bo iteration

Introduce and use a helper to iterate over the various pinned bo lists.
There are a couple of slight functional changes:

1) GGTT maps are now performed with the bo locked.
2) If the per-bo callback fails, keep the bo on the original list.

v2:
- Skip unrelated change in xe_bo.c

Cc: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250321133709.75327-1-thomas.hellstrom@linux.intel.com