drm/amd/display: fix cursor disappearing after resume

Since during suspend, the cursor registers are cleared,
once the system resumes back, the cursor remains disabled.
cursor_set_attributes() only sets the cursor attributes
along with cursor size and surface address, but does not
enable the cursor back on.

We need to save the current cursor location so that
we can resume back to the same location. This is done
in dm_crtc_cursor_move(), where we save the current
cursor location into cursor_x and cursor_y. Later during
resume we use these same values to set the cursor
position along with cursor attributes.

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>