staging: lustre: Remove typedef and update cfs_hash_bd struct

Remove typedef keyword and rename the cfs_hash_bd_t struct to
cfs_hash_bd in libcfs_hash.h. These changes resolve the
"Do not add new typedefs" warning generated by checkpatch.pl
and meet kernel coding style.

Struct variables in other header and source files that depend
on libcfs_hash.h are updated as well.

Signed-off-by: Lisa Nguyen <lisa@xenapiadmin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>