net: qualcomm: fix QCA7000 checksum handling

Based on tests the QCA7000 doesn't support checksum offloading. So assume
ip_summed is CHECKSUM_NONE and let the kernel take care of the checksum
handling. This fixes data transfer issues in noisy environments.

Reported-by: Michael Heimpold <michael.heimpold@in-tech.com>
Fixes: 291ab06e ("net: qualcomm: new Ethernet over SPI driver for QCA7000")
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: David S. Miller <davem@davemloft.net>