mips64: Support for Cavium-specific load indexed instructions

Support for lhux, lwux, lbx for Cavium.

Patch by Zahid Anwar, with style changes.

Related to Bugzilla issue 326444.



git-svn-id: svn://svn.valgrind.org/vex/trunk@2811 8f6e269a-dfd6-0310-a8e1-e2731360e62c