drm/ttm: merge ttm_bo_api.h and ttm_bo_driver.h v2

Merge and cleanup the two headers into a single description of the
object API. Also move all the documentation to the implementation and
drop unnecessary includes from the header.

No functional change.

v2: minimal checkpatch.pl cleanup

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221125102137.1801-4-christian.koenig@amd.com