wifi: mwifiex: Fix RF calibration data download from file

wifi: mwifiex: Fix RF calibration data download from file

This patch resolves an issue where RF calibration data from a
file could not be downloaded to the firmware. The feature to
download calibration data from a file was broken by the commit:
d39fbc88956e.

The issue arose because the function `mwifiex_cmd_cfg_data()`
was modified in a way that prevented proper handling of
file-based calibration data. While this patch restores the ability
to download RF calibration data from a file, it may inadvertently
break the feature to download calibration data from the device
tree. This is because the function `mwifiex_dnld_dt_cfgdata()`,
which also relies on `mwifiex_cmd_cfg_data()`, is still used for
device tree-based calibration data downloads.

Fixes: d39fbc88956e ("mwifiex: remove cfg_data construction")
Signed-off-by: Jeff Chen <jeff.chen_1@nxp.com>
Link: https://patch.msgid.link/20250318050739.2239376-3-jeff.chen_1@nxp.com
[add newline for shorter lines]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>