net/i40e: relax barrier in Tx
net/i40e: relax barrier in Tx

To keep ordering of mixed accesses, rte_cio is sufficient.
The rte_io barrier inside the I40E_PCI_REG_WRITE is overkill.[1]

[1] http://inbox.dpdk.org/dev/CALBAE1M-ezVWCjqCZDBw+MMDEC4O9
qf0Kpn89EMdGDajepKoZQ@mail.gmail.com

Fixes: 4861cde46116 ("i40e: new poll mode driver")
Cc: stable@dpdk.org

Signed-off-by: Gavin Hu <207ee22c2cf71e20c5b5df8395050c07c07d8709@arm.com>
Reviewed-by: Jerin Jacob <352c4d4f9291b869992ddb67daa45ddc149fed30@marvell.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk