drm/amdgpu: remove unneeded semicolon

No functional modification involved.

./drivers/gpu/drm/amd/amdgpu/nbio_v7_9.c:146:2-3: Unneeded semicolon.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=4871


Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>