arch-power: Added support for Atomic Instructions

arch-power: Added support for Atomic Instructions

Add support for Load and Reserve and Store Conditional Instructions:

* Load Byte And Reserve Indexed.
* Store Byte Conditional Indexed.
* Load Halfword And Reserve Indexed.
* Store Halfword Conditional Indexed.
* Load Word And Reserve Indexed.
* Store Word Conditional Indexed.
* Load Doubleword And Reserve Indexed.
* Store Doubleword Conditional Indexed.

Change-Id: I1dac94928e7a1bb6f458a4ecea0fca3247b26d37
Signed-off-by: Kajoljain379 <kajoljain797@gmail.com>