staging: wilc1000: use BIT macro

This patch addresses the checkpatch warning advising the usage of the
BIT macro for Bit shift operation.

Signed-off-by: Hari Prasath Gujulan Elango <hgujulan@visteon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>