Stopped the C128 mouse drivers from blocking certain keys such as '1', '2', and 'Q'.

This extra fix is needed because the C128 keyboard scanner works a little differently than the C64 scanner works.
Fixes #696. Fixes #853.

libsrc/c128/mou/c128-joy.s

@@ -3,7 +3,7 @@
 ;
 ; 2009-09-26, Ullrich von Bassewitz
 ; 2014-04-26, Christian Groessler
-; 2014-05-01, Greg King
+; 2020-07-14, Greg King
 ;
 
         .include        "zeropage.inc"
@@ -379,7 +379,7 @@ IOCTL:  lda     #<MOUSE_ERR_INV_IOCTL     ; We don't support ioctls for now
 IRQ:    jsr     CPREP
         lda     KEY_COUNT
         sta     old_key_count
-        lda     #$7F
+        lda     #$FF
         sta     CIA1_PRA
         lda     CIA1_PRB                ; Read joystick #0
         and     #$1F