[U-Boot] [bug report]cmd: cache: output information

[jk]

Hi guys,

I think the output of command 'dcache' is improper. It always print 
'writethrough' regardless of the real policy, such as write back.

=> dcache
Data (writethrough) Cache is ON

Not only ARM but also other socs support cache, hence we can't 
differentiate policy by macro (i.e CONFIG_SYS_ARM_CACHE_WRITETHROUGH).
Can you think of anything better?