ipmi: Finish cleanup of BMC attributes

The previous cleanup of BMC attributes left a few holes, and if
you run with lockdep debugging with a BMC with the proper attributes,
you could get a warning.

This patch removes all the unused attributes from the BMC structure,
since they are all declared in the .data section now.  It makes
the attributes all static.  It fixes the referencing of the
attributes in a couple of cases that dynamically added the files
depending on BMC information.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: Huang Ying <ying.huang@intel.com>
Tested-by: Alexei Starovoitov <ast@plumgrid.com>