net: mvpp2: fix RSS register definitions

There is no RSS_TABLE register in PPv2 Controller. The register 0x1510
which was specified is actually named "RSS_HASH_SEL", but isn't used by
this driver at all.

Based on how this register was used, it should have been the
RXQ2RSS_TABLE register, which allows to select the RSS table that will
be used for the incoming packet.

The RSS_TABLE_POINTER is actually a field of this RXQ2RSS_TABLE
register.

Since RSS tables are actually not used by the driver for now, this
commit does not fix a runtime bug.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>