drm/amdgpu: fix semicolon.cocci warnings

drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c:608:2-3: Unneeded semicolon

 Remove unneeded semicolon.

Generated by: scripts/coccinelle/misc/semicolon.cocci

Fixes: b4a7db71 ("drm/amdgpu: add per device user friendly xgmi events for vega20")
CC: Jonathan Kim <jonathan.kim@amd.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>