iwlwifi: move the creation of LQ host command to iwlcore

This patch moves creation of LQ host command to iwlcore
from previous location in rate scaling.

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