drm/amdgpu/gfx: fix cleaner shader IB buffer overflow

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/gfx: fix cleaner shader IB buffer overflow The cleaner shader sysfs path allocates a 16-dword (64 byte) IB but incorrectly fills (align_mask + 1) dwords. On GFX rings align_mask is 0xff, so the loop wrote 256 dwords into a 64-byte buffer, causing a kernel page fault. The IB only needs to be a minimal NOP shell to schedule the job; the cleaner shader itself is emitted on the ring via emit_cleaner_shader(). Fill 16 dwords to match the allocation. v2: Use ib_size_dw variable (Lijo) (cherry picked from commit bf21af331ebf72d0935fd70c73192414a422c03a)