drm/amdgpu: fix bo->pin leaking in amdgpu_bo_create_reserved

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: fix bo->pin leaking in amdgpu_bo_create_reserved amdgpu_bo_create_reserved() only allocates a new BO when *bo_ptr (struct amdgpu_bo **bo_ptr as input parameter) is NULL, it simply skips creation when *bo_ptr is non-NULL. But it unconditionally reserves, pins, gart allocates and maps the BO afterwards. When the same non-NULL BO pointer is passed in again, for example firmware buffers that live in adev and are re-loaded on every resume / cp_resume / start under AMDGPU_FW_LOAD_DIRECT, amdgpu_bo_pin() just increases pin_count unconditionally, however the matching teardown only unpins once, so pin_count never drops to zero, so TTM is not able to move, swap or evict a BO, causing BO leaks. This commit fixes this issue by only pinning the bo once at creation, and repeated calls no longer take additional pin references. (cherry picked from commit 3ddc0ae76202c447b6aec61e907b852bc94671cf)

Where it's fixed