u-boot: v2: Remove the fixed TLB and LAW entrynubmer

Remove the fixed TLB and LAW entry nubmer. Use actually TLB and LAW
entry number to control the loop.  This can reduce the potential risk
for the 85xx processor increasing its TLB adn LAW entry number.

Signed-off-by: Swarthout Edward <swarthout@freescale.com>
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>