net: ena: change sizeof() argument to be the type pointer

net: ena: change sizeof() argument to be the type pointer

BugLink: http://bugs.launchpad.net/bugs/1701575
Instead of using:
memset(ptr, 0x0, sizeof(struct ...))
use:
memset(ptr, 0x0, sizeor(*ptr))

Signed-off-by: Netanel Belgazal <netanel@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 917501109cf4ea4c47991f593111338811369bf5 net-next)
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>