[Core/VDP] reverted stupid DMA fill timing modification introduced in https://github.com/ekeeke/Genesis-Plus-GX/commit/9a0a1c29223c672681c9655dd09418e99c2faead (fixes DMA fill regression)

core/vdp_ctrl.c

@@ -2464,9 +2464,6 @@ static void vdp_68k_data_w_m5(unsigned int data)
       dma_length = 0x10000;
     }
 
-    /* Take into account initial data word processing */
-    dma_length += 2;
-
     /* Trigger DMA */
     vdp_dma_update(m68k.cycles);
   }