drm/amd/display: remove redundant msg to pmfw at boot/resume

[why & how]
this is to remove redundant msg to pmfw at boot/resume
since bios already power up dcn.

Reviewed-by: Chris Park <chris.park@amd.com>
Signed-off-by: Charlene Liu <Charlene.Liu@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>