Change kernel to use none target

I forgot that the CI still uses the stock cc65 which doesn't support my
target. The kernel doesn't really need this target though, only the user
programs.

sw/kernel/Makefile

@@ -1,5 +1,5 @@
 CC=cl65
-CFLAGS=-T -t super6502 -I. --cpu "65C02"
+CFLAGS=-T -t none -I. --cpu "65C02"
 test: CFLAGS=-T -t sim65c02 -I.
 LDFLAGS=-C link.ld -m $(NAME).map
 SIM=sim65