net: cavium: liquidio: fix up "Avoid dma_unmap_single on uninitialized ndata"

This fixes up commit 1d1cb762 which was
commit 8e6ce7ebeb34f0992f56de078c3744fb383657fa upstream.

Ben writes:
	This goto should not have been changed, as no DMA mapping has been
	attempted at this point in the function.

	This seems to have been fixed upstream by commit 6a885b60dad2 "liquidio:
	Introduce new octeon2/3 header".  I leave it to you to work out how it
	should be fixed in 4.4-stable.

Fix this up by hand, as the referenced patch isn't worthy of being
backported.

Reported-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>