net: mvpp2: define the number of RSS entries per table in mvpp2.h

The size of the the RSS indirection tables should be defined in mvpp2.h,
so that we can use it in all files of the PPv2 driver.

This commit moves the define in mvpp2.h, and adds the missing #include
in mvpp2_cls.h.

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