drm/gma500: Move gma_intel_crtc_funcs into gma_display.c

All functions live in gma_display.c already so move the vtable. Also
shorten the name to gma_crtc_funcs.

Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220317092555.17882-2-patrik.r.jakobsson@gmail.com