staging: wfx: fix cast operator

Sparse detects that le16_to_cpup() expects a __le16 * as argument.

Change the cast operator to be compliant with sparse.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200512150414.267198-4-Jerome.Pouiller@silabs.com


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