Driver: Vmxnet3: Update Rx ring 2 max size

Device emulation supports max size of 4096.

Signed-off-by: Shrikrishna Khare <skhare@vmware.com>
Signed-off-by: Bhavesh Davda <bhavesh@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>