smsc75xx: fix smsc75xx_set_features()

smsc75xx: fix smsc75xx_set_features()

BugLink: http://bugs.launchpad.net/bugs/1786352
[ Upstream commit 88e80c62671ceecdbb77c902731ec95a4bfa62f9 ]

If an attempt is made to disable RX checksums, USB adapter is changed
but netdev->features is not, because smsc75xx_set_features() returns a
non zero value.

This throws errors from netdev_rx_csum_fault() :
<devname>: hw csum failure

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steve Glendinning <steve.glendinning@shawell.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>