iwlwifi: iwl-fh.h cleanup

This patch fix value of upper FH register bound plus
it reorders and groups registers in more readable way

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Acked-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>