[LinuxBIOS] Machine Check Exception with ECC DIMMs on MCP55 board

[Lu, Yinghai]

Only Opteron supports ECC.

About mem training
0: BSP will train memory on all nodes of ReceiverEn, then train memory
nodes of DQSPos
1: every core0 will train memory on the node itself. 
2: BSP will train memory on one node (ReceiverEn, DQSPos) and then next
Node.

For big system ( Four way or quad way system), you can save time with
Option 1.

YH