m68k/sun3: Remove is_medusa and m68k_pgtable_cachemode

Did TODO to clean the kernel code a bit.
Signed-off-by: Ruslan Isaev <ubijca16@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/kernel/sun3-head.S

@@ -88,9 +88,3 @@ kpt:
         .long 0
 availmem:
         .long 0
-| todo: remove next two. --m
-is_medusa:
-        .long 0
-m68k_pgtable_cachemode:
-        .long 0
-