[U-Boot] Sparc build warnings

[Peter Tyser]

Hi Marek,

> I just recently got the following issues when building Sparc platforms with 
> debian gcc 4.7.1-5. Peter, you seems to be involved, can you please check on 
> these?

I'm not involved with these boards or Sparc, so not sure if I'm much
help.  I believe Dan Hellstrom is the best cantidate (added to CC).

Most the the warnings look pretty trivial to fix, so I could gin
something up, but I don't have a Sparc toolchain to actually test any
modifications.

Best,
Peter