iwlwifi: send DC calib config to runtime ucode

Since uCode is responsible for doing DC calibration, there's no need
to let init uCode to do initial DC calibration then send results
back to driver, then driver sends the results to runtime uCode.
Driver can simply tell runtime uCode to do DC calibration.

Actually, this patch does not disable DC calib for init uCode. It just
prevent driver from saving and sending the DC calib results (from init
ucode) to runtime uCode. The driver still uses 0xffffffff in
CALIB_CFG_CMD for init ucode.

Signed-off-by: Shanyu Zhao <shanyu.zhao@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>