staging: wfx: prefer ARRAY_SIZE instead of a magic number

When possible, we prefer to use the macro ARRAY_SIZE rather than hard
coding the number of elements.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200505123757.39506-12-Jerome.Pouiller@silabs.com


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