wifi: cfg80211: fix memory leak in query_regdb_file()

In the Linux kernel, the following vulnerability has been resolved:

wifi: cfg80211: fix memory leak in query_regdb_file()

In the function query_regdb_file() the alpha2 parameter is duplicated

using kmemdup() and subsequently freed in regdb_fw_cb(). However,

request_firmware_nowait() can fail without calling regdb_fw_cb() and

thus leak memory.