arch-power: Add fixed-point byte-reversed load and store instructions
This adds the following load and store instructions:
* Load Halfword Byte-Reverse Indexed (lhbrx)
* Load Word Byte-Reverse Indexed (lwbrx)
* Load Doubleword Byte-Reverse Indexed (ldbrx)
* Store Halfword Byte-Reverse Indexed (sthbrx)
* Store Word Byte-Reverse Indexed (stwbrx)
* Store Doubleword Byte-Reverse Indexed (stdbrx)
Change-Id: I9f211bb4e3007ca09002a9ba4e5afb4b2e67cddd
Signed-off-by: Sandipan Das <sandipan@linux.vnet.ibm.com>