drm/amdgpu: Fix the BO release clear memory warning

This happens when the amdgpu_bo_release_notify running
before amdgpu_ttm_set_buffer_funcs_status set the buffer
funcs to enabled.

check the buffer funcs enablement before calling the fill
buffer memory.

v2:(Christian)
  - Apply it only for GEM buffers and since GEM buffers are only
    allocated/freed while the driver is loaded we never run into
    the issue to clear with buffer funcs disabled.

v3:(Mario)
  - drop the stable tag as this will presumably go into a
    -fixes PR for 6.10

Log snip:
*ERROR* Trying to clear memory with ring turned off.
RIP: 0010:amdgpu_bo_release_notify+0x201/0x220 [amdgpu]

Fixes: a68c7eaa

 ("drm/amdgpu: Enable clear page functionality")
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Tested-by: Richard Gong <richard.gong@amd.com>
Suggested-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610180401.9540-1-Arunpravin.PaneerSelvam@amd.com