drm/amd/display: Remove duplicate dcn401/dcn401_clk_mgr.h header

./drivers/gpu/drm/amd/display/dc/clk_mgr/dcn401/dcn401_clk_mgr.c: dcn401/dcn401_clk_mgr.h is included more than once.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=8885


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