ati-vga: Remove dst_x/y updates after blit

The Mobility M6 register reference (DST_HEIGHT_WIDTH) states that dst_y is
updated after a blit but this appears to not be the case.

Hardware testing revealed that both the R128 and R100 do not update
dst_x or dst_y after a blit, regardless of the source. This removes
the update.

Signed-off-by: Chad Jablonski <chad@jablonski.xyz>
Reviewed-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-ID: <20260303024730.1489136-8-chad@jablonski.xyz>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

hw/display/ati_2d.c

@@ -174,10 +174,6 @@ void ati_2d_blt(ATIVGAState *s)
                                     dst_y * surface_stride(ds),
                                     s->regs.dst_height * surface_stride(ds));
         }
-        s->regs.dst_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
-                         dst_x + s->regs.dst_width : dst_x);
-        s->regs.dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
-                         dst_y + s->regs.dst_height : dst_y);
         break;
     }
     case ROP3_PATCOPY:
@@ -228,8 +224,6 @@ void ati_2d_blt(ATIVGAState *s)
                                     dst_y * surface_stride(ds),
                                     s->regs.dst_height * surface_stride(ds));
         }
-        s->regs.dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
-                         dst_y + s->regs.dst_height : dst_y);
         break;
     }
     default: