Re-add support for lbarx, lharx, stbcx. and sthcx. insns back to the E6500 cpu.

Re-add support for lbarx, lharx, stbcx. and sthcx. insns back to the E6500 cpu.

opcodes/
	PR binutils/20196
	* ppc-opc.c (powerpc_opcodes <lbarx, lharx, stbcx., sthcx.>): Enable
	opcodes for E6500.

gas/
	PR binutils/20196
	* gas/testsuite/gas/ppc/e6500.s <lbarx, lharx, lwarx, ldarx,
	stbcx., sthcx., stwcx., stdcx.>: Add tests.
	* gas/testsuite/gas/ppc/e6500.d: Likewise.
	* gas/testsuite/gas/ppc/power8.s: Likewise.
	* gas/testsuite/gas/ppc/power8.d: Likewise.
	* gas/testsuite/gas/ppc/power4.s <lwarx, ldarx, stwcx.,
	stdcx.>: Add tests.
	* gas/testsuite/gas/ppc/power4.d: Likewise.