net: marvell: prestera: bump supported firmware version to 3.0

New firmware version has some ABI and feature changes like:

    - LAG support
    - initial L3 support
    - changed events handling logic

Signed-off-by: Vadym Kochan <vkochan@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>