[PATCH] iwlwifi: set correct base rate for A band in rs_dbgfs_set_mcs

This patch fixes base rate needed for fixed rate operation in A band

Signed-off-by: Ron Rindjunsky <ron.rindjunsky@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>