staging: rtl8723au: remove unnecessary le32_to_cpu

The values passed to le32_to_cpu are already in the correct byte order.
This fixes four "cast to restricted __le32" sparse warnings.

Signed-off-by: Michał Bartoszkiewicz <mbartoszkiewicz@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>