ETHTOOL: Fix UFO typo

The function ethtool_get_ufo was referring to ETHTOOL_GTSO instead of
ETHTOOL_GUFO.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Adrian Bunk <bunk@stusta.de>