Some of the parameters are set by the driver in little endian. For instance, in cfg80211.c, the following code statement has been written:
/* data sent to dongle has to be little endian */
*(__le32 *)buf = cpu_to_le32(WL_BSS_INFO_MAX);
err = brcmf_fil_cmd_data_get(ifp, BRCMF_C_GET_BSS_INFO,
You can check for cpu_to_le32() for little endian and be32_to_cpu() for big endian.
Also a side note, we have not tested the FMAC driver for kernel v5.9.