Staging: silicom: Fixed error 'do not initialise statics to 0 or NULL'.

This patch fixes error 'do not initialise statics to 0 or NULL'. found by
checkpatch in driver silicom.

Signed-off-by: Tülin İzer <tulinizer@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>