qede: Fix memset corruption

Thanks to Kees Cook who detected the problem of memset that starting
from not the first member, but sized for the whole struct.
The better change will be to remove the redundant memset and to clear
only the msix_cnt member.

Signed-off-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
Signed-off-by: Ariel Elior <aelior@marvell.com>
Signed-off-by: Shai Malin <smalin@marvell.com>
Reported-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>