drm/nouveau/disp: Move tiling functions to dispnv50/tile.h

Refactor, and move the tiling geometry functions to dispnv50/tile.h,
so they can be re-used by drm_panic.
No functional impact.

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241022185553.1103384-3-jfalempe@redhat.com