Fix for powerpc-power.exp gdb regression test for Power 9

Fix for powerpc-power.exp gdb regression test for Power 9

The GDB testsuite reports 5 test failures on Power 7 instructions.
Additionally the ppc test is missing the new Power 9 instructions as
well as a large number of older instructions.  Additionally, some
instruction names have changed or been deleted.  This patch
fixes the test failures and completely updates the test to make it
consistent with the supported Power 9 instructions listed in:

   gas/testsuite/gas/ppc/power7.d
   gas/testsuite/gas/ppc/power8.d
   gas/testsuite/gas/ppc/power9.d
   gas/testsuite/gas/ppc/altivec.d
   gas/testsuite/gas/ppc/altivec2.d
   gas/testsuite/gas/ppc/altivec3.d
   gas/testsuite/gas/ppc/vsx.d
   gas/testsuite/gas/ppc/vsx2.d
   gas/testsuite/gas/ppc/vsx3.d
-----------------------------------------------------

gdb/testsuite/ChangeLog

2016-08-18  Carl Love  <cel@us.ibm.com>

	* gdb.arch/powerpc-power.s: Add new Power9 instruction tests
	and sync up the test with tests in gas/testsuite/gas/ppc.
	* gdb.arch/powerpc-power.exp: Likewise.