net: mvpp2: mvpp2_percpu_read_relaxed() can be static

Fixes: db9d7d36 ("net: mvpp2: Split the PPv2 driver to a dedicated directory")
Signed-off-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>