drm/ttm: rework on ttm_resource to use size_t type

Change ttm_resource structure from num_pages to size_t size in bytes.
v1 -> v2: change PFN_UP(dst_mem->size) to ttm->num_pages
v1 -> v2: change bo->resource->size to bo->base.size at some places
v1 -> v2: remove the local variable
v1 -> v2: cleanup cmp_size_smaller_first()
v2 -> v3: adding missing PFN_UP in ttm_bo_vm_fault_reserved

Signed-off-by: Somalapuram Amaranath <Amaranath.Somalapuram@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221027091237.983582-1-Amaranath.Somalapuram@amd.com
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>