drm/amdgpu: Enable clear page functionality

Add clear page support in vram memory region.

v1(Christian):
  - Dont handle clear page as TTM flag since when moving the BO back
    in from GTT again we don't need that.
  - Make a specialized version of amdgpu_fill_buffer() which only
    clears the VRAM areas which are not already cleared
  - Drop the TTM_PL_FLAG_WIPE_ON_RELEASE check in
    amdgpu_object.c

v2:
  - Modify the function name amdgpu_ttm_* (Alex)
  - Drop the delayed parameter (Christian)
  - handle amdgpu_res_cleared(&cursor) just above the size
    calculation (Christian)
  - Use AMDGPU_GEM_CREATE_VRAM_WIPE_ON_RELEASE for clearing the buffers
    in the free path to properly wait for fences etc.. (Christian)

v3(Christian):
  - Remove buffer clear code in VRAM manager instead change the
    AMDGPU_GEM_CREATE_VRAM_WIPE_ON_RELEASE handling to set
    the DRM_BUDDY_CLEARED flag.
  - Remove ! from amdgpu_res_cleared(&cursor) check.

v4(Christian):
  - vres flag setting move to vram manager file
  - use dma_fence_get_stub in amdgpu_ttm_clear_buffer function
  - make fence a mandatory parameter and drop the if and the get/put dance

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Suggested-by: Christian König <christian.koenig@amd.com>
Acked-by: Felix Kuehling <felix.kuehling@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240419063538.11957-2-Arunpravin.PaneerSelvam@amd.com


Signed-off-by: Christian König <christian.koenig@amd.com>