drm/radeon: stop using pages with drm_prime_sg_to_page_addr_arrays v2

This is deprecated.

v2: also use ttm_sg_tt_init to avoid allocating the page array.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/403832/