drm/amd/display: remove unneeded semicolon

Eliminate the following coccicheck warning:
./drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c:2344:67-68: Unneeded semicolon

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>