CVE-2026-68110 drm/amdgpu/sdma4.4.2: replace BUG_ON() with WARN_ON()

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/sdma4.4.2: replace BUGON with WARNON There's no need to crash the kernel for these cases. cherry picked from commit fa4f86a148271e325e95287630a3a15a9cd35fdc...