drm/gpusvm: Make drm_gpusvm_for_each_* macros public

The drm_gpusvm_for_each_notifier, drm_gpusvm_for_each_notifier_safe and
drm_gpusvm_for_each_range_safe macros are useful for locating notifiers
and ranges within a user-specified range. By making these macros public,
we enable broader access and utility for developers who need to leverage
them in their implementations.

v2 (Matthew Brost)
- drop inline __drm_gpusvm_range_find
- /s/notifier_iter_first/drm_gpusvm_notifier_find

Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20250819162058.2777306-5-himal.prasad.ghimiray@intel.com