Always cache EMEMAP/SUPMAP in PU_HUDGFX tag

These particular patches need to be cached in
K_LoadKartHUDGraphics, but caching them anywhere else with a
different tag causes them to potentially be freed and then later
use-after-freed during a Sealed Star run, causing a crash. Instead,
let's cache them as PU_HUDGFX in all cases where they are used.

Fixes KartKrew/Kart#1240