drm/amd/display: Program cursor regs after context swapped.

Cursor is abnormal after pipe_ctx is changed in context.
Cause: cursor attributes is programmed right after front end
programming, but it use old pipe_ctx to program which is not
updated yet.
Solution:
Program cursor regs after context swapped.

Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>