[Keyboard] Fix Print Screen key for XT to USB converter (#7039)

* Fix Print Screen key for XT to USB converter

* While I'm here, get rid of led.c as it does absolutely nothing

* Fix info.json too

* "]" key is 1.25U and stepped on the Model F XT

keyboards/converter/xt_usb/rules.mk

@@ -23,7 +23,7 @@ NKRO_ENABLE      = yes  # USB Nkey Rollover
 XT_ENABLE        = yes
 CUSTOM_MATRIX    = yes
 
-SRC = matrix.c led.c
+SRC += matrix.c
 
 # Optimize size but this may cause error "relocation truncated to fit"
 #EXTRALDFLAGS = -Wl,--relax