Use constants for rBGPI+rOBPI auto-increment

Fix some documentation

engine/debug.asm

@@ -161,19 +161,19 @@ Function819a7: ; 819a7
 	ld de, BGPals
 	ld bc, 16 palettes
 	call CopyBytes
-	ld a, $80
+	ld a, 1 << rBGPI_AUTO_INCREMENT
 	ld [rBGPI], a
 	ld hl, Palette_819f4
-	ld c, $40
+	ld c, 8 palettes
 	xor a
 .asm_819c8
 	ld [rBGPD], a
 	dec c
 	jr nz, .asm_819c8
-	ld a, $80
+	ld a, 1 << rOBPI_AUTO_INCREMENT
 	ld [rOBPI], a
 	ld hl, Palette_81a34
-	ld c, $40
+	ld c, 8 palettes
 .asm_819d6
 	ld a, [hli]
 	ld [rOBPD], a