Error on lmw, lswi and related PowerPC insns when LE

Error on lmw, lswi and related PowerPC insns when LE

	* config/tc-ppc.c (md_assemble): Error for lmw, stmw, lswi, lswx,
	stswi, or stswx in little-endian mode.
	* testsuite/gas/ppc/476.d,
	* testsuite/gas/ppc/476.s: Delete lmw, stmw, lswi, lswx, stswi, stswx.
	* testsuite/gas/ppc/a2.d,
	* testsuite/gas/ppc/a2.s: Move lmw, stmw, lswi, lswx, stswi, stswx..
	* testsuite/gas/ppc/be.d,
	* testsuite/gas/ppc/be.s: ..to here, new big-endian only test.
	* testsuite/gas/ppc/le_error.d,
	* testsuite/gas/ppc/le_error.l: New little-endian test.
	* testsuite/gas/ppc/ppc.exp: Run new tests.

(cherry picked from commit 86c0f617ac5f3a5f4aab76c7f90255254ca27576)