Clean up XXX comments for unused content

engine/events/kurt.asm

@@ -163,7 +163,7 @@ Kurt_SelectQuantity: ; 880c2
 	db 09, 06 ; start coords
 	db 12, 19 ; end coords
 
-	db 0, 0, -1, 0 ; XXX
+	db 0, 0, -1, 0 ; unused
 
 .PlaceApricornName: ; 88116
 	call MenuBoxCoord2Tile

engine/events/mom_phone.asm

@@ -217,7 +217,7 @@ endr
 
 INCLUDE "data/items/mom_phone.asm"
 
-	db 0, 0, 0 ; XXX
+	db 0, 0, 0 ; unused
 
 _MomText_HiHowAreYou: ; 0xfd1b1
 	; Hi,  ! How are you?
@@ -255,10 +255,10 @@ _MomText_ItsInRoom: ; 0xfd1ca
 	db "@"
 ; 0xfd1cf
 
-	db 0 ; XXX
+	db 0 ; unused
 
 Predef3A: ; fd1d0
 	ret
 ; fd1d1
 
-	ret ; XXX
+	ret ; unused

engine/events/overworld.asm

@@ -1749,7 +1749,7 @@ Script_GetOnBike_Register: ; 0xd14e
 	special ReplaceKrisSprite
 	end
 
-; XXX
+; unused
 	nop
 	ret