drm/amdgpu: prefer snprintf over sprintf

drm/amdgpu: prefer snprintf over sprintf

This will trade the W=1 warning -Wformat-overflow to
-Wformat-truncation. This lets us enable -Wformat-overflow subsystem
wide.

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Pan, Xinhui <Xinhui.Pan@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/fea7a52924f98b1ac24f4a7e6ba21d7754422430.1704908087.git.jani.nikula@intel.com