[PATCH] iwlwifi: add supp_rates to rate scale sta private data

This patch adds supp_rate bit mask to rate scale sta private data structre
and thus removes sta from the argument list in helper functions.

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