net: Zeroing the structure ethtool_wolinfo in ethtool_get_wol()

memset() the structure ethtool_wolinfo that has padded bytes
but the padded bytes have not been zeroed out.

Change-Id: If3fd2d872a1b1ab9521d937b86a29fc468a8bbfe
Signed-off-by: Avijit Kanti Das <avijitnsec@codeaurora.org>

idea is taken here - https://github.com/rmbq/android_kernel_htc_msm8960/commit/c241af8e212455351e3badb4c12108241b6a0913