target-m68k: Fix cmpa operand size

"The size of the operation can be specified as word or long.
Word length source operands are sign-extended to 32 bits for
comparison."

So comparison is always done using OS_LONG.
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

target-m68k/translate.c

@@ -2170,7 +2170,7 @@ DISAS_INSN(cmpa)
     }
     SRC_EA(env, src, opsize, 1, NULL);
     reg = AREG(insn, 9);
-    gen_update_cc_cmp(s, reg, src, opsize);
+    gen_update_cc_cmp(s, reg, src, OS_LONG);
 }
 
 DISAS_INSN(eor)