accel: Use XArray instead of IDR for minors

accel: Use XArray instead of IDR for minors

Accel minor management is based on DRM (and is also using struct
drm_minor internally), since DRM is using XArray for minors, it makes
sense to also convert accel.
As the two implementations are identical (only difference being the
underlying xarray), move the accel_minor_* functionality to DRM.

Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Acked-by: James Zhu <James.Zhu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240823163048.2676257-3-michal.winiarski@intel.com
Signed-off-by: Christian König <christian.koenig@amd.com>