drm/amd/display: fix 270 degree rotation for mixed-SLS mode

[Why]
When we rotate 270 in mixed SLS mode, the recouts occupy the
right side of the display.  So all the recout_skip_v values
are relative to the left side of the display.  This causes
adjust_vp_and_init_for_seamless_clip() to incorrectly increase
the data->viewport.height for that recout.  The rotation looks
like the bottom half is duplicated twice.

[How]
recout.x values are being adjusted based on
stream->timing.h_border_left.  Instead of using h_border_left,
use dst.x to represent the border.  Shift dst.x by the amount of
stream->timing.h_border_left and set
stream->timing.h_border_left to 0.  Do all the calculations
and then revert stream->timing.h_border_left and
stream->dst.x back to their original values.
When calculating pipe_ctx->plane_res.scl_data.h_active,
make sure to use the original stream->timing.h_border_left
value.

Signed-off-by: Samson Tam <Samson.Tam@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>