drm/amd/display: Fix function banner for amdgpu_dm_psr_disable_all()

[WHY]
Incorrect function name in function banner.

[HOW]
Correct name and brief description.

Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>