drm/amd/display: clean up and simply locking logic

always take update lock instead of using HW built in update
lock trigger with write to primary_addr_lo.

we will be a little more inefficient with the extra registers
write to lock, but this simplify code and make it always correct.

Will revisit locking optimization once update sequence mature

Signed-off-by: Tony Cheng <tony.cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>