Disallow PC relative for CMPI on MC68000/10

Disallow PC relative for CMPI on MC68000/10

The MC68000/10 decodes the second operand of CMPI strictly as destination
operand, which disallows PC relative addressing, even though the insn
doesn't write to the operand.  This restriction has only been lifted for
the MC68020+ and CPU32.

opcodes:
	PR 25848
	* m68k-opc.c (m68k_opcodes): Allow pc-rel for second operand of
	cmpi only on m68020up and cpu32.

gas:
	PR 25848
	* testsuite/gas/m68k/operands.s: Add tests for cmpi.
	* testsuite/gas/m68k/operands.d: Update.
	* testsuite/gas/m68k/op68000.d: Update for new error messages.