net: mvpp2: always compare hw-version vs MVPP21

Currently we have PP2v1 and PP2v2 hw-versions, with some different
handlers depending upon condition hw_version = MVPP21/MVPP22.
In a future there will be also PP2v3. Let's use now the generic
"if equal/notEqual MVPP21" for all cases instead of "if MVPP22".

This patch does not change any functionality.
It is not intended to introduce PP2v3.
It just modifies MVPP21/MVPP22 check-condition
bringing it to generic and unified form correct for new-code
introducing and PP2v3 net-next generation.

Signed-off-by: Stefan Chulski <stefanc@marvell.com>
Acked-by: Marcin Wojtas <mw@semihalf.com>
Signed-off-by: David S. Miller <davem@davemloft.net>