staging: wfx: fix endianness of the field 'channel_number'

staging: wfx: fix endianness of the field 'channel_number'

The field 'channel_number' from the structs hif_ind_rx and hif_req_start
is a __le32. Sparse complains this field is not always correctly
accessed:

    drivers/staging/wfx/data_rx.c:95:55: warning: incorrect type in argument 1 (different base types)
    drivers/staging/wfx/data_rx.c:95:55:    expected int chan
    drivers/staging/wfx/data_rx.c:95:55:    got restricted __le16 const [usertype] channel_number

However, the value of channel_number cannot be greater than 14 (this
device only support 2.4Ghz band). So, we only have to access to the
least significant byte. It is finally easier to declare it as an array
of bytes and only access to the first one.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200512150414.267198-17-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>