net: thunderx: fix constants

This fixes sparse messages like this:

drivers/net/ethernet/cavium/thunder/thunder_bgx.c:897:24: sparse:
constant 0x300000000000 is so big it is long

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@caviumnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>