staging: wfx: avoid defining array of flexible struct

In this particular case, the struct element is already flexible struct.
Thus struct element ie[] is ambiguous inside another struct. The members
of struct element ie aren't being accessed in code anywhere. The data of
u8 type is copied in it. So it has been changed to u8 ie[] to make the
sparse happy and code simple.

Warning from sparse:
drivers/stagingwfx/hif_tx.c: note: in included file (through drivers/stagingwfx/data_tx.h, drivers/staging//wfx/wfx.h):
drivers/staging//wfx/hif_api_cmd.h:103:26: warning: array of flexible structures

Reviewed-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Signed-off-by: Muhammad Usama Anjum <musamaanjum@gmail.com>
Link: https://lore.kernel.org/r/20210211105026.GA45458@LEGION


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