wifi: mwifiex: Initialize the chan_stats array to zero

wifi: mwifiex: Initialize the chan_stats array to zero

The adapter->chan_stats[] array is initialized in
mwifiex_init_channel_scan_gap() with vmalloc(), which doesn't zero out
memory.  The array is filled in mwifiex_update_chan_statistics()
and then the user can query the data in mwifiex_cfg80211_dump_survey().

There are two potential issues here.  What if the user calls
mwifiex_cfg80211_dump_survey() before the data has been filled in.
Also the mwifiex_update_chan_statistics() function doesn't necessarily
initialize the whole array.  Since the array was not initialized at
the start that could result in an information leak.

Also this array is pretty small.  It's a maximum of 900 bytes so it's
more appropriate to use kcalloc() instead vmalloc().

Cc: stable@vger.kernel.org
Fixes: bf35443314ac ("mwifiex: channel statistics support for mwifiex")
Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/20250815023055.477719-1-rongqianfeng@vivo.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>