staging: wfx: make hif_ie_table_entry const

In wfx_update_filtering(), filter_ies is never modified. So, make it
constant.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200406111756.154086-11-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>