staging: wfx: remove useless #ifdef

In the old days, this file was shared with other projects. Obviously,
this "#ifdef __KERNEL__" have no reasons to be in the kernel.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20220113085524.1110708-8-Jerome.Pouiller@silabs.com


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